Add deprecated field

What does this MR do?

Would you @smichels be OK with manually marking packages as deprecated when somebody asks you to? I would like to be able to mark lib-compiler-itasks as deprecated so that Cloogle can stop indexing it, but the proposal in nitrile#37 (closed) seems rather complicated.

• Fixes API endpoints other than GET /api/packages (broken since 66414030)
• Adds a deprecated field to the database, with API and frontend support

Changes to public APIs

• Packages returned from GET /api/packages and GET /api/packages/NAME now have a boolean deprecated field

To update, you need to manually add the field. Also, please mark base-compiler-itasks and lib-compiler-itasks as deprecated by setting the corresponding field to 1.

Author's checklist (required)

• Intermediate commits compile (use git rebase -i main if not)
• Newly added code has a style consistent with the rest of the repository
• Newly added code is documented (guidelines)

Related issues

Closes nitrile#37 (closed).