[PM-11766] Introduce SDK client (#10974)

Integrate the SDK into our other clients.

libs/common/src/platform/abstractions/sdk/sdk.service.ts

@@ -0,0 +1,8 @@
+import { Observable } from "rxjs";
+
+import { BitwardenClient } from "@bitwarden/sdk-internal";
+
+export abstract class SdkService {
+  client$: Observable<BitwardenClient>;
+  supported$: Observable<boolean>;
+}