Finish inbound E2E device lists (#1243)

* Add tests for device list updates

* Add stale_device_lists table and use db before asking remote for device keys

* Fetch remote keys if all devices are requested

* Add display_name col to store remote device names

Few other tweaks to make `Server correctly handles incoming m.device_list_update`
pass.

* Fix sqlite otk bug

* Unbuffered channel to block /send causing sytest to not race anymore

* Linting and fix bug whereby we didn't send updated dl tokens to the client causing a tightloop on /sync sometimes

* No longer assert staleness as Update blocks on workers now

* Back out tweaks

* Bugfixes

keyserver/storage/sqlite3/storage.go

@@ -41,10 +41,15 @@ func NewDatabase(dataSourceName string) (*shared.Database, error) {
 	if err != nil {
 		return nil, err
 	}
+	sdl, err := NewSqliteStaleDeviceListsTable(db)
+	if err != nil {
+		return nil, err
+	}
 	return &shared.Database{
-		DB:               db,
-		OneTimeKeysTable: otk,
-		DeviceKeysTable:  dk,
-		KeyChangesTable:  kc,
+		DB:                    db,
+		OneTimeKeysTable:      otk,
+		DeviceKeysTable:       dk,
+		KeyChangesTable:       kc,
+		StaleDeviceListsTable: sdl,
 	}, nil
 }