Check for records being language overlays of sys_language_uid=-1 records #129
Description
This is a kinda common scenario: When there is a record in sys_language_uid=0 and there are localizations, and the sys_language_uid=0 record is later changed to sys_language_uid=-1, this may end up with "dangling" localizations.
Add checks to verify localized records never point to -1 records. Probably related existing checks that may need a look or extended tests: TcaTablesTranslatedLanguageParentDeleted, TcaTablesTranslatedLanguageParentDifferentPid, TcaTablesTranslatedLanguageParentMissing