Clean up module

[DieterHolvoet]

General stuff

• [x] Cleanup code using wieni/wmcodestyle
• [x] Normalise composer.json
• [x] Add LICENSE in case it's missing. Also add the license to composer.json.
• [x] Add CHANGELOG.md (and UPGRADING.md, if applicable)
• [x] Add issue & pull request templates
• [x] Update repo description & tags
• [x] Update README
• [x] Update .gitignore
• [x] Check dependencies: ensure composer.json has a php & drupal/core version requirements and add missing requirements to the .info file
• [x] Clean up branches (check SourceGraph for usages across projects)

Code to check for relevance

• [x] cdnless.patch
• [x] pager stuff:
  • wmcontroller_preprocess_pager
  • wmcontroller_theme_registry_alter
  • Drupal\wmcontroller\EventSubscriber\PagerRewriteSubscriber
• [x] ViewBuilder::createOriginalRenderArrayFromEntity
  • [x] setHeadElements
  • [x] addHeadElement
  • [x] setHooks
  • [x] getHooks
  • [x] addHeadElementsToRenderArray
  • [x] addCustomHooksToRenderArray

[RobinHoutevelts]

cdnless.patch

• [x] I'll check which projects use this. I think it's good to delete this