Fix Required Builds merge check by switching to repo-scoped Bitbucket…

[asmild]

Use repo-scoped Bitbucket builds API to fix Required Builds merge check

The plugin currently uses the deprecated /rest/build-status/1.0/commits/{sha} endpoint,
which does not work with Bitbucket's "Required Builds" merge check — builds appear on
commits but are not recognized as satisfying merge requirements.

This PR switches to the repo-scoped /rest/api/latest/projects/{project}/repos/{repo}/commits/{sha}/builds
endpoint and adds the parent field to the payload.

Changes:

• New BuildStatusUriFactory.create() overload for repo-scoped API
• Auto-detect project key and repo slug from Git remote URL
• Add parent field to notification payload (required for Required Builds matching)
• Accept HTTP 200-299 responses (new API returns 200, not 204)
• Fall back to legacy API when project/repo cannot be determined

Testing done

• All existing 76 tests pass, new unit tests added for:
  • Repo-scoped URI construction
  • HTTP 200/201/204 success and 400/500 failure responses
  • Git remote URL parsing (HTTPS, SSH, SCP-style, personal repos)
• Manual testing against Bitbucket Data Center with Required Builds merge check enabled

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira — Fixes Bitbucket 7.15 RestAPI update #290
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed