Implement test-set-driven bot runs against configured test projects
### Problem/Motivation
Make the bot's test execution always run against the projects defined in test-projects.yml, allowing fine-grained selection of test modules for validation. Wire the test-set branch as the source for verifying bot changes and add support for pushing test tags to enable testing against custom test modules.
### Work items
- Commit(s): [7a4c8f0341](https://git.drupalcode.org/project/project_analysis/-/commit/7a4c8f034109), [3d21701d23](https://git.drupalcode.org/project/project_analysis/-/commit/3d21701d2353), [0ffdae3c10](https://git.drupalcode.org/project/project_analysis/-/commit/0ffdae3c109a), [9ba3502681](https://git.drupalcode.org/project/project_analysis/-/commit/9ba3502681c8), [f180343b11](https://git.drupalcode.org/project/project_analysis/-/commit/f180343b114b), [0d29f172c0](https://git.drupalcode.org/project/project_analysis/-/commit/0d29f172c05c), [13cbda2b1f](https://git.drupalcode.org/project/project_analysis/-/commit/13cbda2b1fe4), [e68020eb78](https://git.drupalcode.org/project/project_analysis/-/commit/e68020eb78d9), [9e49b98d79](https://git.drupalcode.org/project/project_analysis/-/commit/9e49b98d79ac), [0f1271359a](https://git.drupalcode.org/project/project_analysis/-/commit/0f1271359a60), [70210119c8](https://git.drupalcode.org/project/project_analysis/-/commit/70210119c832), [cb48884d29](https://git.drupalcode.org/project/project_analysis/-/commit/cb48884d29b8)
### Credit
- Implemented by: @bbrala
- Test-project feedback: @goba, @nicxvan, @wimleers, @rfay, @larowlan
---
*Filed retroactively as part of the Drupal 12 rector coverage effort. Closed as fixed; credit to be applied to the contributors listed above.*
*AI was used extensively to build this work and to file this issue. See [Dries Buytaert: AI-generated Rector rules for Drupal](https://dri.es/ai-generated-rector-rules-for-drupal) and [Björn Brala: Drupal Rector rules are config, not code. Mostly.](https://www.linkedin.com/pulse/drupal-rector-rules-config-code-mostly-bj%C3%B6rn-brala-vfpwe/).*
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