Update publish bicep step to run on environment (#8026)

# Description

This updates the build.yaml workflow to run on a Github environment
during the publish bicep step. We currently have credentials set up for
ref paths/branches but this requires a lot of credentials to be added
for each pull/push case (i.e. we need a credential for PRs, pushes to
main, release branches/tags, etc). Switching to an environment
streamlines these credentials into one environment-based credential.

See here for more details on the Github Actions setup:
https://learn.microsoft.com/en-us/azure/app-service/deploy-github-actions?tabs=openid%2Caspnetcore#1-generate-deployment-credentials

## Type of change

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- This pull request is a minor refactor, code cleanup, test improvement,
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Fixes: #issue_number

## Contributor checklist
Please verify that the PR meets the following requirements, where
applicable:

- [ ] An overview of proposed schema changes is included in a linked
GitHub issue.
- [ ] A design document PR is created in the [design-notes
repository](https://github.com/radius-project/design-notes/), if new
APIs are being introduced.
- [ ] If applicable, design document has been reviewed and approved by
Radius maintainers/approvers.
- [ ] A PR for the [samples
repository](https://github.com/radius-project/samples) is created, if
existing samples are affected by the changes in this PR.
- [ ] A PR for the [documentation
repository](https://github.com/radius-project/docs) is created, if the
changes in this PR affect the documentation or any user facing updates
are made.
- [ ] A PR for the [recipes
repository](https://github.com/radius-project/recipes) is created, if
existing recipes are affected by the changes in this PR.

---------

Signed-off-by: sk593 <[email protected]>

.github/workflows/build.yaml

@@ -265,6 +265,7 @@ jobs:
   build-and-push-bicep-types:
     name: Publish Radius bicep types to ACR
     runs-on: ubuntu-latest
+    environment: publish-bicep
     steps: 
       - name: Check out code
         uses: actions/checkout@v4