[TASK] Integrate frontend rendering functional tests

To ensure that actions in the backend have an accordant and
correct impact in the frontend, a frontend request needs to
be triggered from the functional test execution.
The response of that simulated frontend request shall be
delivered as JSON, exceptions need to be caught and
forwarded to the test suite as well. Besides that, it is
required to have a possibility to set up TypoScript
configuration, modify TCA and TYPO3_CONF_VARS for further
hook processing.

Resolves: #55882
Releases: 6.2
Change-Id: I54d475e8f1ce01fd7cb8c64b68c2318b1e9f7bbe