[BUGFIX] Create valid file reference index data

This patch prevents the creation of sys_refindex entries that point to no
table and no record.

Additionally it fixes the array structure for the creation of
sys_refindex records for sys_file relations.

For deleted file references no reference will be created between
sys_file and the referenced table.

The configuration for the uid_foreign field was changed from a select
field for tt_content records to a normal input field to prevent the
creation of invalid refindex data. To which table uid_foreign is
pointing depends on the tablenames field.

To make sure both sides of the relation of a sys_file_reference appear
in the refindex table the exclusion of sys_file_reference as
foreign_table is removed.

Resolves: #53712
Releases: 6.2, 6.1, 6.0
Change-Id: Ic864ade10e4e97fbd9017b9c779be68d911dd626
Reviewed-on: https://review.typo3.org/26645
Reviewed-by: Markus Klein
Tested-by: Markus Klein