feat: add devtools metrics

Adds a metrics implementation that broadcasts metrics to a browser
DevTools plugin.

packages/metrics-devtools/LICENSE

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+This project is dual licensed under MIT and Apache-2.0.
+
+MIT: https://www.opensource.org/licenses/mit
+Apache-2.0: https://www.apache.org/licenses/license-2.0

packages/metrics-devtools/LICENSE-APACHE

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+Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

packages/metrics-devtools/LICENSE-MIT

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+The MIT License (MIT)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

packages/metrics-devtools/README.md

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+# @libp2p/devtools-metrics
+
+[![libp2p.io](https://img.shields.io/badge/project-libp2p-yellow.svg?style=flat-square)](http://libp2p.io/)
+[![Discuss](https://img.shields.io/discourse/https/discuss.libp2p.io/posts.svg?style=flat-square)](https://discuss.libp2p.io)
+[![codecov](https://img.shields.io/codecov/c/github/libp2p/js-libp2p.svg?style=flat-square)](https://codecov.io/gh/libp2p/js-libp2p)
+[![CI](https://img.shields.io/github/actions/workflow/status/libp2p/js-libp2p/main.yml?branch=main\&style=flat-square)](https://github.com/libp2p/js-libp2p/actions/workflows/main.yml?query=branch%3Amain)
+
+> Collect libp2p metrics and send them to browser DevTools
+
+# About
+
+<!--
+
+!IMPORTANT!
+
+Everything in this README between "# About" and "# Install" is automatically
+generated and will be overwritten the next time the doc generator is run.
+
+To make changes to this section, please update the @packageDocumentation section
+of src/index.js or src/index.ts
+
+To experiment with formatting, please run "npm run docs" from the root of this
+repo and examine the changes made.
+
+-->
+
+Configure your browser-based libp2p node with DevTools metrics:
+
+```typescript
+import { createLibp2p } from 'libp2p'
+import { devToolsMetrics } from '@libp2p/devtools-metrics'
+
+const node = await createLibp2p({
+  metrics: devToolsMetrics()
+})
+```
+
+Then use the [DevTools plugin](https://github.com/ipfs-shipyard/js-libp2p-devtools)
+for Chrome or Firefox to inspect the state of your running node.
+
+# Install
+
+```console
+$ npm i @libp2p/devtools-metrics
+```
+
+## Browser `<script>` tag
+
+Loading this module through a script tag will make it's exports available as `Libp2pDevtoolsMetrics` in the global namespace.
+
+```html
+<script src="https://unpkg.com/@libp2p/devtools-metrics/dist/index.min.js"></script>
+```
+
+# API Docs
+
+- <https://libp2p.github.io/js-libp2p/modules/_libp2p_devtools_metrics.html>
+
+# License
+
+Licensed under either of
+
+- Apache 2.0, ([LICENSE-APACHE](https://github.com/libp2p/js-libp2p/blob/main/packages/metrics-devtools/LICENSE-APACHE) / <http://www.apache.org/licenses/LICENSE-2.0>)
+- MIT ([LICENSE-MIT](https://github.com/libp2p/js-libp2p/blob/main/packages/metrics-devtools/LICENSE-MIT) / <http://opensource.org/licenses/MIT>)
+
+# Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

packages/metrics-devtools/package.json

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+{
+  "name": "@libp2p/devtools-metrics",
+  "version": "0.0.0",
+  "description": "Collect libp2p metrics and send them to browser DevTools",
+  "author": "",
+  "license": "Apache-2.0 OR MIT",
+  "homepage": "https://github.com/libp2p/js-libp2p/tree/main/packages/metrics-devtools#readme",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/libp2p/js-libp2p.git"
+  },
+  "bugs": {
+    "url": "https://github.com/libp2p/js-libp2p/issues"
+  },
+  "publishConfig": {
+    "access": "public",
+    "provenance": true
+  },
+  "type": "module",
+  "types": "./dist/src/index.d.ts",
+  "files": [
+    "src",
+    "dist",
+    "!dist/test",
+    "!**/*.tsbuildinfo"
+  ],
+  "exports": {
+    ".": {
+      "types": "./dist/src/index.d.ts",
+      "import": "./dist/src/index.js"
+    }
+  },
+  "eslintConfig": {
+    "extends": "ipfs",
+    "parserOptions": {
+      "project": true,
+      "sourceType": "module"
+    }
+  },
+  "scripts": {
+    "clean": "aegir clean",
+    "lint": "aegir lint",
+    "dep-check": "aegir dep-check",
+    "doc-check": "aegir doc-check",
+    "build": "aegir build",
+    "test": "aegir test -t browser",
+    "test:chrome": "aegir test -t browser --cov"
+  },
+  "dependencies": {
+    "@libp2p/interface": "^1.3.1",
+    "@libp2p/interface-internal": "^1.2.1",
+    "@libp2p/logger": "^4.0.12",
+    "@libp2p/simple-metrics": "^1.0.1",
+    "multiformats": "^13.1.0"
+  },
+  "devDependencies": {
+    "@libp2p/peer-id-factory": "^4.1.1",
+    "aegir": "^42.2.5",
+    "race-event": "^1.3.0",
+    "sinon-ts": "^2.0.0"
+  },
+  "sideEffects": false
+}