Evaluate dropping custom handling of `MaxTokenExpirationSeconds` in favour of replacing it with CEL expression

[dimityrmirchev]

What would you like to be added:
We have custom handling for checking the max validity of a token (ref). We should evaluate replacing this using a CEL expression in a ClaimValidationRule. In addition we should think if the check using iat and exp claims is actually valid as nbf claim might be the actual claim that defines the start of the token validity.

Additional relevant documentation:

• Kubernetes Structured Authentication
• Common Expression Language