refactor(filemanager): compile database and migrations

[mmalenic]

Closes #530

Changes

• A running postgres database is no longer required to compile filemanager (reducing some compile times and hopefully repetitive compilations too).
  • sqlx queries no longer use macros and instead use runtime functions.
  • sea-orm entities are still generated by filemanager-build, however as a separate step to build.rs. The entities are checked into the codebase, and are assumed to be up to date when running deployment related steps. When developing in the filemanager directory, a database connection is still required to refresh the entities.
• Filemanager migrations are squashed.

[mmalenic]

This PR should also close #532.

[victorskl]

LGTM