[TASK] Introduce Enum constants for t3ver_state

Currently the t3ver_state field can have 6
different integer values.
To clean up the code and make it better
understandable a Enum object is implemented.

Resolves: #52551
Releases: 6.2
Change-Id: I2f41d6bbf6575aec4a5c2b6d86495700d61bf5b7
Reviewed-on: https://review.typo3.org/24410
Reviewed-by: Sebastian Fischer
Tested-by: Sebastian Fischer
Reviewed-by: Thorsten Kahler
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn