Assign ownership to many libs files (#6928)

Assign ownership to many of the remaining libs/common files.

Criteria for ownership:
* Files used by a single team, is now owned by that team.
* Files related to a domain owned by a team is now owned by that team.
* Where ownership is unclear the "lowest level" service takes ownership.

libs/angular/src/platform/services/theming/theming.service.abstraction.ts

@@ -0,0 +1,12 @@
+import { Observable } from "rxjs";
+
+import { ThemeType } from "@bitwarden/common/platform/enums";
+
+import { Theme } from "./theme";
+
+export abstract class AbstractThemingService {
+  theme$: Observable<Theme>;
+  monitorThemeChanges: () => Promise<void>;
+  updateSystemTheme: (systemTheme: ThemeType) => void;
+  updateConfiguredTheme: (theme: ThemeType) => Promise<void>;
+}