Generate ATT&CK navigator layer files and links (#1787)

* Generate attack layer files and build with package
* add update-navigator-gists command
* add workflow to update navigator gists on pushes to main
* Add coverage readme
* fix keys for links
* update navigator layer names
* purge gist files prior to update; add badge
* Update how the navigator links are displayed
* moved navigator code to dedicated and refactored to dataclasses
* convert gist links to permalink versions
* alphabetize; catch 404 for gist update

(cherry picked from commit 254b4eb23f)

.github/workflows/pythonpackage.yml

@@ -49,3 +49,8 @@ jobs:
       run: |
         python -m detection_rules test
 
+    - name: Update navigator gist files
+      env:
+        GITHUB_TOKEN: "${{ secrets.NAVIGATOR_GIST_TOKEN }}"
+      if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
+      run: python -m detection_rules dev update-navigator-gists