[BUGFIX] Fix incomplete mocking in ResourceStorage test

Due to a not mocked FileRepository object, a warning
is issued which leads to a failed test.

Add a FileRepository mock and clean up all usage
of the FileRepository in ResourceStorage.

Fixes: #44439
Releases: 6.0, 6.1

Change-Id: I214fce4635d452764bd9edc8e11f863bd76961a6
Reviewed-on: https://review.typo3.org/17508
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel
Reviewed-on: https://review.typo3.org/17509
[TASK] Remove references to oldstyle Login News (TYPO3_CONF_VARS)

Adding Login News via
$GLOBALS['TYPO3_CONF_VARS']['BE']['loginNews'] is not longer
supported but there are still references to it in the code that should be
removed.

Resolves: #44506
Releases: 6.0, 6.1

Change-Id: I2c91c3209dc4a1dc55e570e569825acb3167150e
Reviewed-on: https://review.typo3.org/17519
Reviewed-by: Mattias Nilsson
Tested-by: Mattias Nilsson
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
[BUGFIX] array_merge_recursive_overrule: __UNSET for array values

Using __UNSET on keys that hold array values does not unset them.
However the documentation does not mention this restriction.
Therefore this is considered a bug and fixed by this patch.

Resolves: #43874
Releases: 6.1, 6.0, 4.7

Change-Id: Ie9f96c6f608da7e91fec2bc639dba9f3bcc8f426
Reviewed-on: https://review.typo3.org/17096
Reviewed-by: Markus Klein
Reviewed-by: Wouter Wolters
Reviewed-by: Tobias Liebig
Tested-by: Tobias Liebig