Generate: TF can now accept custom logits processors
# What does this PR do?

TF generation test addition PR 1 (out of ???).

In an effort to move generation integration tests to be framework-agnostic, I'll be adding low-hanging fruit to TF. This PR brings custom logits processors to TF `.generate()`. The code added is almost copy-paste from PT.
_The documentation is not available anymore as the PR was closed or merged._