Summary:
This diff discounts indirect changes for access control purposes. A UserAction that updates a cell A, which in turn causes changes in other dependent cells, will be considered a change to cell A for access control purposes.
The `engine.apply_user_actions` method now returns a `direct` array, with a boolean for each `stored` action, set to `true` if the action is attributed to the user or `false` if it is attributed to the engine. `GranularAccess` ignores actions attributed to the engine when checking for edit rights.
Subtleties:
* Removal of references to a removed row are considered direct changes.
* Doesn't play well with undos as yet. An action that indirectly modifies a cell the user doesn't have rights to may succeed, but it will not be reversible.
Test Plan: added tests, updated tests
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2806
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
