[!!!][TASK] Make prefill work when a request is not cached, but caching is enabled

[pschriner]

Prefill cannot be used when caching is enabled even when it is safe to do so (because an action is called that is uncached).
This patch allowes using prefill when caching is enabled (good for situations with EXT:sfc & powermail forms that are included via Typoscript)

[mschwemer]

Hi Patrick

Thanks for your contribution. I am sorry to decline your PR. Why?

My / our main concern is, that there might be the possibility that user contributed data gets cached. Only with the TYPO3 core it will probably work. But you never don't know what people do and how they hack the caching stuff. ;-)

If there is any issue, this will fall back to powermail and we will have to test, argue and so on ... even if that is not reproducable in a standard installation.

As this works for you, you can still apply this via composer patches for example.