Started scap sync-world: Backport for [[gerrit:1275997|Promote CM6 out of beta, remove CM5 modules, and add v6 aliases (T373720)]], [[gerrit:1276002|VisualEditor.CodeMirror.less: remove CM5 styles]], [[gerrit:1276004|CodeEditorHooks: remove temporary code for CodeMirror beta feature (T419332)]], [[gerrit:1276005|DescriptionField: use new module name for loading CodeMirror]], [[gerrit:1275998|Ho