[TASK] Reduce complexity in frontend functional tests

Testing the frontend behavior in functional tests creates
currently an own PHP sub-request to execute TypoScript in
frontent context.
Several hooks collect called cObjects and try to find the
correct nesting levels. Albeit this is working for the
current tests, it is way too complex for extending the
tests for further scenarios like for FAL and Extbase.

The hook magic is resolved and explicit render functions,
called via TypoScript, collect the data an output aggregated
JSON data in the end. Besides that the PHP sub-request
execution now re-uses the PHPUnit utilities to determine
and run the accordant executables.

Resolves: #59487
Releases: 6.2
Change-Id: Ic9eeadee5471a3e0e40d2dffb69b38dec16a0aa1
[TASK] Integrate functional DataHandler tests for FAL

The functional frontend tests are extended with basic FAL
use-cases in the live workspaces, as well as for modifying,
publishing single records and publishing all records in a
particular workspaces scenario.

The frontend is tested by using the TypoScript FILES cObject.

Resolves: #59276
Releases: 6.2
Change-Id: I3a1e59f70015b1168e4f29458c8d6ff77c0b3dcf