[TASK] Switch isset() and is_array() to null coalesce

Several hundred function calls and vast numbers
of indentations can be saved by using the null
coalesce operator instead of checking empty/array.

Change-Id: I38f2ce2de83a454aaa0d16c771014b6de84b3f7a
Releases: master
Resolves: #80812
Reviewed-on: https://review.typo3.org/52416


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>