Unify usage of fe_group in tables of TYPO3 core
The column "fe_group" is defined as varchar everywhere in the core except in table "sys_collection".
This will cause some problems with some DBMS (e.g. PostgreSQL) as the FrontendGroupRestriction::class will generate a query which will e.g. check against empty string.
Thus the column "fe_group" should be unified to varchar.
The following tests fail with the column "fe_group" defined as integer:
[BUGFIX] Convert fe_group in sys_collection to VARCHAR
The core methods dealing with frontend group restrictions expect this
field to be of a character based datatype. Comparing an integer based
field with string triggers query errors on PostgreSQL which
does not perform implict type conversions.
Reviewed-by: Benni Mack <email@example.com>
Tested-by: Benni Mack <firstname.lastname@example.org>