Block API users

[michielp1807]

Closes #349

TODO:

• Block users in backend
• Add unit tests for blocked accounts
• Update admin interface to allow blocking accounts
• The admin interface can now also be used to delete API users (closes Delete ApiUser from admin interface #117)
• Fix playwright tests for admin interface
• Consider adding a "full freeze" block status to organizations

[codecov]

Codecov Report

❌ Patch coverage is 85.18519% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/api/oauth/handlers.rs	0.00%	5 Missing ⚠️
src/api/api_users.rs	90.90%	2 Missing ⚠️
src/api/auth.rs	91.66%	1 Missing ⚠️

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