Adapt route to add proposed actions

[gabegma]

Part of #297

Description:

• New route to import proposed actions

Remaining

• Adapt call to update tags in the front end.

Checklist:

You should check all boxes before the PR is ready. If a box does not apply, check it to acknowledge it.

• ISSUE NUMBER. You linked the issue number (Ex: Resolve #XXX).
• PRE-COMMIT. You ran pre-commit on all commits, or else, you
  ran pre-commit run --all-files at the end.
• USER CHANGES. The changes are added to CHANGELOG.md and the documentation, if they impact
  our users.
• DEV CHANGES.
  • Update the documentation if this PR changes how to develop/launch on the app.
  • Update the README files and our wiki for any big design decisions, if relevant.
  • Add unit tests, docstrings, typing and comments for complex sections.

[JosephMarinier]

Very very good! So satisfying! Thank you!
I only have comments on variable names, from a second pair of (fresh) eyes.

[gabegma]

Should the front-end be reviewed before merging @JosephMarinier?

[JosephMarinier]

I think the front end is fine. It was very straightforward.

[JosephMarinier]

You can give camelCase to the API. That's what the front end does. Two changes...