[feature] Add comprehensive tests and docs for CI failure bot #524

- Add complete test suite with comprehensive coverage for all bot functions
- Consolidate documentation into reusable-github-utils.rst as requested by maintainer
- Move CI failure bot code from .github/scripts to openwisp_utils package
- Add github_actions extra dependency group in setup.py for proper installation
- Fix test imports to use correct openwisp_utils.ci_failure_bot module path
- Remove noqa comments from Gemini prompt to avoid sending linting artifacts to AI
- Implement dynamic branch detection using repo.default_branch instead of hardcoded master
- Add null check for deleted fork repositories to prevent AttributeError
- Make Gemini API key optional with graceful fallback to static responses
- Simplify workflow error handling and clean up formatting
- Address all CodeRabbit feedback on exception handling and code quality
- Follow OpenWISP documentation patterns with proper structure

Addresses all maintainer comments and CodeRabbit suggestions for production readiness.

Closes #524

Author: Srinath0916

.github/scripts/ci_failure_bot.py

@@ -27,9 +27,8 @@ jobs:
           python-version: "3.11"
 
       - name: Install dependencies
-        # Pin dependency versions for reproducibility
         run: |
-          pip install requests>=2.31.0 PyGithub>=2.0.0 google-generativeai>=0.3.0
+          pip install -e .[github_actions]
 
       - name: Run CI Failure Bot
         env:
@@ -38,4 +37,8 @@ jobs:
           WORKFLOW_RUN_ID: ${{ github.event.workflow_run.id }}
           REPOSITORY: ${{ github.repository }}
           PR_NUMBER: ${{ github.event.workflow_run.pull_requests[0].number || '' }}
-        run: python .github/scripts/ci_failure_bot.py
+        run: |
+          set -e  # Exit immediately if any command fails
+          echo "Starting CI Failure Bot..."
+          python -m openwisp_utils.ci_failure_bot
+          echo "CI Failure Bot completed successfully"