This introduces a simple garbage collection which checks for all soft
deleted bookmarks (`removed = 1`) which have been marked for garbage
collection more than 30 days ago from the time of bootstapping the
messenger.
Closes#2705
These APIs are being introduced to address #2706 and #2704, provided
that clients will move to using these APIs instead of the currently
provided equivalent APIs in the browser service.
The `bookmarks` table is being extended with a `deleted_at` field which
can later be used for garbage collection, as "removing" a bookmark is
merely soft deletion and doesn't actually remove the data from the
database.
In addition to those APIs adding and soft deleting bookmark entries,
they also automatically perform a sync operation to ensure that
bookmarks are synced in real-time (#2704).
Closes#2706, #2704
Pascal Precht