Merge branch 'develop' into ddev-0.20

* develop:
  Fix execution of opcache reset on deploy
  Remove uppercase CSS from mail templates
  Remove return annotation
  Add validation of username to not allow capital chars
  Remove empty line
  [SECURITY] Update TYPO3 CMS to 8.7.17
  Remove obsolete return statement
  Improve code, use core methods, use Hook instead of Controller
  [TASK] add php_cs.cache to gitignore
  [BUGFIX] fix cgl errors
  [FEATURE] Reactivate user process
  [TASK] Register Hook reactivateOldUser
  [WIP] Add workflow button for listview
  [TASK] Add module icon
  [TASK] Add TCA for old user table
  [TASK] Add PID to table structure