[TASK] Testing `brushes` TS setup removal with LanguageItems
[TASK] Adding LanguageSetting to update script suite
[TASK] Implementing first draft of BrushDdiscovery
[TASK] Improving Update suite
[TASK] Improving LanguageItems flexform item processing
[TASK] First draft of BrushRegistry as a Service
[CLEANUP] CGL + CodeSniffer fixes
[TASK] BrushRegistry rendering tests with hooks/markers
[TASK] BrushDiscovery evolutes: work out identifer/alias structure
[TASK] Dependency handling in Registry; provided by Discovery
[TASK] Updating Unit tests
[TASK] Discovery improvements

All depending classes uses the ObjectManager or uses it through Extbase DIC (fx
the SignalSlot dispatcher for the BrushRegistry slot)
[TASK] Testing PageRenderer integration, switching to page. TS cObj
[FIX] Adding `plain` brush identifier - alias map entries
[FIX] Fixing LanguageSetting updater + templates

Only brushes from current active Highlighter must be selected.
[CLEANUP] Removal of cache entry
[TASK] Improving Unit test suite + configuration

Related: #60899
[TASK] Adding phpcs / CodeSniffer execution to documentation
[TASK] Backend templates into sub-folder, adding StandaloneBackendView
[FIX] Fixing LanguageItem retrieval lifecycle memory