ci: Initial BuildAutomation module implementation

[michalChrobot]

Purpose of this PR

This PR removes local implementation of Build Automation and replaces it with a RecipeEngine module that was created in order to consolidate and easily share this functionality

Jira ticket

Not really listed there but related to https://jira.unity3d.com/browse/MTT-15054

Documentation

N/A

Testing & QA (How your changes can be verified during release Playtest)

I will make the builds as usual to double check that everything works the same as before

Up-port

N/A

Backports

Done

[u-pr]

⚠️ Some settings were ignored in '.pr_agent.toml (repository root)' repo settings

Check the configuration's TOML syntax, permitted settings, and size limit. See the error below.

---

Error message:
Ignored prohibited settings: github_app.handle_pr_actions. Permitted settings were applied.

Configuration content:

# This is the configuration for the u-pr bot
# https://github.cds.internal.unity3d.com/unity/u-pr
# For configuration of this file:
# https://developer.portal.internal.unity.com/catalog/default/component/u-pr/docs/configuration/automatic_runs/

[github_app]
handle_pr_actions = ['opened', 'ready_for_review']  # PR events that auto-run pr_commands
pr_commands       = ["/harness-review"]             # what runs on those events
reviewer_commands = ["/harness-review"]             # what runs when @u-pr is added as reviewer

[u-pr]

💡 Harness Review

The generated build workflow is internally coherent, but existing automation does not yet fully account for its new outputs and contract.

The reachable release-preparation flow still points every jobDefinition at the deleted .yamato/project-builders/project-builders.yml, so Step 3 gets non-success responses for all sample launches; the trigger helper only logs these failures and continues, allowing a release to proceed without playtest builds. Update ReleaseConfig to use the new file and lowercase job IDs, and migrate its platform/backend keys, editor matrix, and obsolete Burst option to the new contract.

_{Reviewed commit 9767c54}

_{🤖 Helpful? 👍/👎}