databroker: refactor databroker to sync all changes (#1879)

* refactor backend, implement encrypted store

* refactor in-memory store

* wip

* wip

* wip

* add syncer test

* fix redis expiry

* fix linting issues

* fix test by skipping non-config records

* fix backoff import

* fix init issues

* fix query

* wait for initial sync before starting directory sync

* add type to SyncLatest

* add more log messages, fix deadlock in in-memory store, always return server version from SyncLatest

* update sync types and tests

* add redis tests

* skip macos in github actions

* add comments to proto

* split getBackend into separate methods

* handle errors in initVersion

* return different error for not found vs other errors in get

* use exponential backoff for redis transaction retry

* rename raw to result

* use context instead of close channel

* store type urls as constants in databroker

* use timestampb instead of ptypes

* fix group merging not waiting

* change locked names

* update GetAll to return latest record version

* add method to grpcutil to get the type url for a protobuf type

integration/backends/httpdetails/main.go

@@ -61,6 +61,7 @@ func main() {
 	}
 }
 
+// Result is a result used for rendering.
 type Result struct {
 	Headers    map[string]string `json:"headers"`
 	Method     string            `json:"method"`