[TASK] Activate 'Flush system caches' with Preset 'Development'

Add a new configuration in Install Tool (['SYS']['clearCacheSystem']).
If set, the toolbar of clearing system cache is visible (only for
admin users).

Add it also for Configuration Preset. For Production it is set to FALSE,
for Development it is set to TRUE.

Resolves: #57230
Releases: 6.2
Change-Id: Id45496c6bc1e64b4454ed7ff78e8db1179387b0f
Reviewed-on: https://review.typo3.org/30656
Reviewed-by: Krzysztof Adamczyk
Tested-by: Krzysztof Adamczyk
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers