Summary:
- Add a method `getSnapshotWindow` to `IInventory` and `DocSnapshotInventory`. It returns a `SnapshotWindow`, which represents a duration of time for which we keep backups for a particular document.
- `DocSnapshotPruner` calls this method and passes the window to `shouldKeepSnapshots` to determine which document versions have fallen outside the window and should be pruned.
- The implementation passed to `DocSnapshotInventory` uses a new method `getDocProduct` in `HomeDBManager` which directly returns the `Product` associated with a document, given only the document ID. Other methods in `HomeDBManager` require passing more information, especially about a user, but `DocSnapshotPruner` only knows about document IDs.
Test Plan: Added a test for `getDocProduct` and a test for `DocSnapshotPruner` where `getSnapshotWindow` is specified.
Reviewers: paulfitz
Reviewed By: paulfitz
Differential Revision: https://phab.getgrist.com/D3322
ec8460b772