Keep objects referenced in database

[varmar05]

Summary:

• stop removing project
• keep resolved access requests
• migrate registration_date column to user table
• use user_id in login history
• stop removing users from db
• use user.id in project.removed_by

[coveralls]

Pull Request Test Coverage Report for Build 8154988624

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 29 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+0.07%) to 93.958%

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Files with Coverage Reduction	New Missed Lines	%
server/server/mergin/sync/db_events.py	1	90.91%
server/server/mergin/auth/app.py	2	97.5%
server/server/mergin/sync/workspace.py	2	98.29%
server/server/mergin/tests/test_utils.py	2	98.77%
server/server/mergin/auth/models.py	3	97.06%
server/server/mergin/sync/models.py	7	96.64%
server/server/mergin/sync/permissions.py	12	89.63%

Totals
Change from base Build 8061929893:	0.07%
Covered Lines:	5567
Relevant Lines:	5925

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💛 - Coveralls

[varmar05]

@MarcelGeo could you please verify this does not have impact on frontend?

[MarcelGeo]

For me, schemas are tansparent with .yml . Approve