[TASK] Optimize columns in sys_file_reference

MySQL up to version 5.5 allows at maximum 64 characters for table- 
and fieldnames. Other DBMS allow less. Since MySQL is our primary
database and DBAL could handle specialties.

This patch changes the fields tablenames, fieldname and table_local
to varchar(64) which currently is considered save.

Resolves: #54726
Releases: 6.2
Change-Id: Ic67450a9326dceb413fe694a6233b8c092f70c79
Reviewed-on: https://review.typo3.org/26625
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter