refactor: rename and deprecate database manager

Changes:
- Deprecates SingleConnectionManager and aliases to DatabaseManager.
- Simplifies database config typing in `config.d.ts`.
- Drops implementation specific assert in SingleConnectionManager test.
- Move database prefix reference and drop static property for default value.

Signed-off-by: Minn Soe <contributions@minn.io>

packages/backend/src/index.ts

@@ -29,7 +29,7 @@ import {
   getRootLogger,
   loadBackendConfig,
   notFoundHandler,
-  PluginConnectionDatabaseManager,
+  DatabaseManager,
   SingleHostDiscovery,
   UrlReaders,
   useHotMemoize,
@@ -59,7 +59,7 @@ function makeCreateEnv(config: Config) {
 
   root.info(`Created UrlReader ${reader}`);
 
-  const databaseManager = PluginConnectionDatabaseManager.fromConfig(config);
+  const databaseManager = DatabaseManager.fromConfig(config);
   const cacheManager = CacheManager.fromConfig(config);
 
   return (plugin: string): PluginEnvironment => {