Update package description and some dependencies to use `workspace`
inheritance.
* Also updates circleci to produce dockerhub image.
Closes#1461
Issue #1362
* f touch to retry circleci
* f try to pre-emptively lock protobuf to the older 2.25.2 version
* f force Cargo.lock to use protobuf 2.25.2, dammit
* f move protobuf pin to syncstorage-spanner
* f revert cargo.lock
* f revert #448
* f update base64 / tickle circleci
* f update cadence (and kick circleci)
* f clippy
* f switch to latest google-cloud-rust
* f update to use google-cloud-rust
This is a breaking change. This commit separates syncstorage and tokenserver settings into separate structs that are contained by a parent `Settings` struct. This means that any env vars that hold settings specific to syncstorage (e.g. `SYNC_DATABASE_URL`) have been renamed to `SYNC_SYNCSTORAGE__DATABASE_URL`. Any settings that were moved from the top-level `Settings` struct to the lower level, syncstorage-specific struct will now have a `SYNC_SYNCSTORAGE__` prefix instead of a `SYNC_` prefix.
Closes#1276
