Add support for i18n on Project Activity Page

What does this MR do?

Adds ability to use translations for following parts of Project Activity page

• Tab titles

• Tab tooltips

• Tooltip for RSS button

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

This MR is part of an on-going effort to translate GitLab.

Does this MR meet the acceptance criteria?

• [ ] Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• Tests
  • [ ] Added for this feature/bug
  • All builds are passing
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • [ ] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #32795 (closed)