Frontend for restricting personal access tokens to specific projects

What does this MR do?

• Introduce a project_multi_select VanillaJS component.
• Update personal_access_token form and table with "Projects" field and various UX improvements.
• Update personal_access_token BE with some parameter parsing and validation.

Notes to finish this MR

• This MR is pointed to and based off of the BE branch feature/restricted_personal_access_tokens
• WARNING: You may run into 500 issues when testing this locally. This is because there is a Gitaly N+1 request problem. Here's a way to work around that.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• [ ] API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • [ ] Has been reviewed by a Backend maintainer
  • [ ] Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes #47865 (moved)