Move Project transaction storage to modern tables

Summary:
Ref T4010. Projects have a weird proto-version of ApplicationTransactions which is very similar but not quite the same.

Move the storage to a modern format, but keep all the other code for now.

Test Plan: Migrated project transactions; edited projects.

Reviewers: btrahan, chad

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4010

Differential Revision: https://secure.phabricator.com/D7370