Add database crates

[data-sync-user]

Add the following crates (dependencies are noted as sub-bullets):

• syncstorage-db: Code that neatly combines and exposes the functionality of syncstorage-mysql and synsctorage-spanner for consumption by syncstorage-web
  • syncstorage-mysql: MySQL impls for the database traits in syncstorage-db-common
  • syncstorage-spanner: Spanner impls for the database traits in syncstorage-db-common
• tokenserver-db: Tokenserver database-related code
• syncstorage-mysql
• syncstorage-spanner

syncstorage-db and tokenserver-db should provide an easy-to-use high-level API exposing database functionality. This functionality will eventually be consumed by syncstorage-web and tokenserver-web.

┆Issue is synchronized with this Jira Task

[ddurst]

Test comment in GH.

[data-sync-user]

➤ David Durst commented:

Moved from CONSVC to SYNC as a test.

[data-sync-user]

➤ David Durst commented:

Moved from SYNC back to CONSVC.