7 backports to do

master	10.4	9.5
Merged #67227 [TASK] Make first install compatible with PHP 8 Author Benjamin Franzke Updated 01/04/21, 09:26 Affected Files 7 Patchsets 10 Reviews 3 Verifies 3	#67296 [TASK] Make first install compatible with PHP 8 10.4 Author Jörn Wagner Updated 05/27/21, 20:32 Affected Files 8 Patchsets 6 Reviews Verifies 1
Merged #68766 [BUGFIX] Fix MSSQL support with Doctrine DBAL Author Benni Mack Updated 04/12/21, 20:44 Affected Files 1 Patchsets 2 Reviews 2 Verifies 2	Review is missing.
Merged #64937 [BUGFIX] Apply enableFields in JOIN's ON condition Author Georg Ringer Updated 04/15/21, 12:30 Affected Files 5 Patchsets 6 Reviews 5 Verifies 3	Merged #68740 [BUGFIX] Apply enableFields in JOIN's ON condition 10.4 Author Georg Ringer Updated 04/15/21, 17:08 Affected Files 5 Patchsets 2 Reviews 2 Verifies 2	#68792 [BUGFIX] Apply enableFields in JOIN's ON condition 9.5 Author Markus Klein Updated 06/11/21, 09:46 Affected Files 3 Patchsets 4 Reviews Verifies
Merged #68836 [TASK] Inform about disallowed file extension in image ViewHelpers Author Richard Haeser Updated 04/26/21, 07:30 Affected Files 4 Patchsets 7 Reviews 4 Verifies 4	#68855 [TASK] Inform about disallowed file extension in image ViewHelpers 10.4 Author Richard Haeser Updated 04/26/21, 07:43 Affected Files 4 Patchsets 1 Reviews 2 Verifies
Merged #69155 [BUGFIX] Correct return type for FileReference methods Author Richard Haeser Updated 05/17/21, 13:37 Affected Files 2 Patchsets 2 Reviews 3 Verifies 3	Review is missing.
Merged #69144 [BUGFIX] Normalize UTF-8 strings before calling CharsetConverter->specCharsToASCII() Author Anja Leichsenring Updated 06/17/21, 11:11 Affected Files 5 Patchsets 5 Reviews 5 Verifies 3	Review is missing.
Merged #69974 [TASK] Mitigate downstream CSV code injection Author Oliver Hader Updated 07/20/21, 08:47 Affected Files 3 Patchsets 2 Reviews 2 Verifies 2	Merged #69972 [TASK] Mitigate downstream CSV code injection 10.4 Author Oliver Hader Updated 07/20/21, 08:40 Affected Files 3 Patchsets 2 Reviews 2 Verifies 2	Merged #69971 [TASK] Mitigate downstream CSV code injection 9.5 Author Oliver Hader Updated 07/20/21, 08:40 Affected Files 3 Patchsets 2 Reviews 2 Verifies 2