[GPU][test]: PA token type unit tests refactoring. (#36327)

Added unit tests for page attention's token type feature.

### Details:
- Refactored current PA unit tests to make it possible to extend for new
unittests.
- PA token type unittests are isolated from current ones(but derive as
much as possible from standard PA tests)
 - PA original tests should not be affected in any way

### Tickets:
 - *CVS-188258*

### AI Assistance:
 - *AI assistance used: yes*
- *Initial implementation was done by AI, but after that was seriously
refactored.*

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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: pkowalc1