Add project state store design doc

This follows a similar pattern to projects like Tekton's
enchancement proposal design. This is mostly just for my own personal
use so that I can think through what this thing might look like
once I start implementing it

Signed-off-by: Michael Lieberman <[email protected]>

docs/design/project-state-store.md

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+# Project State Store Design
+
+## Summary
+
+Skootrs needs a way for knowing what actions it has done in creating and managing a project. This is required in order for Skootrs to be able to keep track of what projects it is managing for CRUD purposes.
+
+## Motivation
+
+Currently, all state is stored in a local database on the host running Skootrs. This has multiple problems:
+- If something is changed out of band fro the Skootrs tool it can be difficult to know what has changed.
+- It is impossible to run Skootrs on a project from systems that weren't the one that originally created the project without exporting/importing from the database or copying the database to a new host.
+- It is impossible for someone to audit if someone else has run Skootrs on a project without access to this database.
+- It is impossible for multiple authorized parties to manage the same project through Skootrs
+
+### Goals:
+- Provide mechanism to store and retrieve the state of a Skootrs project This would include:
+    - High level metadata like name of project
+    - List of facets created along with their associated metadata
+- Provide mechanism to give an identifier for a project (e.g. repo url) and have Skootrs be able to manage and audit that project.
+
+### Non-Goals:
+- Provide secure mechanism for ensuring the Skootrs project state can't be modified by unauthorized actors or outside of the Skootrs tool. Eventually this will need to be considered.
+
+## Proposal
+
+There are two main pieces to the proposal:
+- Store the state for a Skootrs project in the repo for the project itself
+- Store a local cache of references to projects the local Skootrs knows about
+
+### In-repo State Store Design
+
+The main idea would be store the entirety of the state as a file inside the repo assuming it's not too big and doesn't change often.
+
+#### File
+
+The proposed solution is to just have a single file with the Skootrs project state inside of the repo. This file should just be called: `./skootrs` and kept in the root of the repo.
+
+#### Structure and Format
+
+The format of the state file should just be json with the structure being just the `InitializedProject` struct.
+
+### Changes to be made
+
+#### Data Model
+
+Various `Initialized` structs will need to be updated to include information on:
+- Hash of the file(s) (if it's a file based facet)
+
+#### Services
+- `SourceBundleFacetService` needs to be updated to also take the hash of the file.
+- Some of the other services will need to be updated to support pulling/pushing 
+
+
+### Local Reference Cache Design
+
+This can just be a simple file called `.skootrscache` with just a list of repo URLs.
+
+## Future
+
+There's a lot of things that can be done to improve on this in the future that could allow for things like:
+- Local caching of project state so you don't have to fetch it every time
+- Having some human readable mapping of project to project url