Add trigger token expiration

What does this MR do and why?

Personal Access Tokens currently provide significantly more functionality than Pipeline Trigger Tokens. This MR is an initial step towards closing the inconsistency between token types by adding an optional expiration date to Pipeline Trigger Tokens.

There has been a significant amount of past discussion surrounding this topic, including the following issues and epics:

• #417111
• #355551
• #36244
• &11155

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Check out this MR
2. Create a pipeline trigger token (project sidebar -> CI/CD -> Pipeline Trigger Tokens -> Expand) with no expiration date and verify that the behavior is the same as the previous behavior.
3. Create a pipeline trigger token with an expiration date in the future and verify that the token shows up, the expiration date is right, and the token can be used.
4. Create a pipeline trigger token with an expiration date in the past and verify that it cannot be used.