Migrate bookmarks database from Python->Go

[orblivion]

See the associated milestone description's for some technical background on this migration.

This migration is for the bookmarks database. Thankfully I didn't put anything else in this sqlite database, so it's fairly simple. The other sqlite database is for the map search index, which we can migrate separately. (I would be worried about two processes accessing the same sqlite database).

As of this writing I've already gotten a start on this. I think I just have to write the internal Go endpoint to handle reads/writes of bookmarks.