Add ability to delete a user's information

[tsmock]

What type of PR is this? (check all applicable)

• 🍕 Feature

Related Issue

Fixes #6002 (backend; frontend UI not done)

Describe this PR

This adds an API call (specifically, a DELETE to /users/<int:user_id> (specific user) and /users (users no longer on OSM)).

As much user-supplied information as possible is redacted, with the following exceptions:

• Projects (specifically of note, project descriptions are not removed)
  • Projects are not reassigned either (maybe this should happen?)
• Tasks (I believe this is would only have task modification times)
• Interests (specifically, interests that the user created)
• Licenses (just in case a license was required by a project)
• User role (admins are downgraded to mappers, blocked users remain blocked)

Screenshots

N/A

Alternative Approaches Considered

Deleting user from database completely. Rejected partially due to complexity of figuring out what to do with mapped/validated tasks and user blocks.

Review Guide

For the code path that redacts users from the DB if the user deleted their account in OSM, user 535043 is known to no longer exist.

Sample psql command for user 535043:

INSERT INTO users VALUES (535043, 'some username', 0, 1, 0, 0, 0, null, 'foobar@example.com', '@meta', true, '@linkedin', '@twitter', NOW(), null, true, false, '@irc', 'London', 'United Kingdom', 'John Doe', '@skype', '@slack', 'ID', true, true, 'https://image.example/png.png', 0, 'a gender here', true, true, true);

$ curl -X DELETE -H 'Authorization: Token ${TOKEN}' localhost:5000/api/v2/users/

Further questions:
Is the OSM server admin team OK with us hitting /user/:id frequently?

EDIT: TomH pointed me at https://planet.openstreetmap.org/users_deleted/users_deleted.txt .

[sonarcloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud