Cache context ignores request attribute changes

Added MR including test coverage. I also verified manually that the change fixes the described issue.

One things that needs a check is that ContentFormatCacheContext needs to implement an interface.

Kernel test is passing.

thx. I addressed your remarks, either fixed or commented - see comments above!

All PR comments are resolved. RTBC

Tested locally and it fixes the issue described in the ticket.

**offtopic** I had some issues testing it locally with the layour_builder integration. Which I had to disable to test.

Automatically closed - issue fixed for 2 weeks with no activity.