Summary:
Adds preferences to orgs. There are a few flavors:
* `userOrgPrefs`: these are specific to a certain user and a certain org.
* `orgPrefs`: these are specific to a certain org, and apply to all users.
* `userPrefs`: these are specific to a certain user, and apply to all orgs.
The three flavors of prefs are reported by `GET` for an org, and can be modified by `PATCH` for an org. The user needs to have UPDATE rights to change `orgPrefs`, but can change `userOrgPrefs` and `userPrefs` without that right since the settings only affect themselves.
Test Plan: added tests
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2572
Summary: This moves enough server material into core to run a home server. The data engine is not yet incorporated (though in manual testing it works when ported).
Test Plan: existing tests pass
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2552
