[PM-16793] port credential generator service to providers (#14071)

* introduce extension service
* deprecate legacy forwarder types
* eliminate repeat algorithm emissions
* extend logging to preference management
* align forwarder ids with vendor ids
* fix duplicate policy emissions; debugging required logger enhancements

-----

Co-authored-by: Daniel James Smith <2670567+djsmith85@users.noreply.github.com>

libs/common/src/tools/state/user-state-subject-dependency-provider.ts

@@ -15,4 +15,9 @@ export abstract class UserStateSubjectDependencyProvider {
   // FIXME: remove `log` and inject the system provider into the USS instead
   /** Provides semantic logging */
   abstract log: <Context extends object>(_context: Jsonify<Context>) => SemanticLogger;
+
+  /** Get the system time as a number of seconds since the unix epoch
+   *  @remarks this can be turned into a date using `new Date(provider.now())`
+   */
+  abstract now: () => number;
 }

libs/common/src/tools/state/user-state-subject.spec.ts

@@ -90,6 +90,7 @@ const SomeProvider = {
   } as LegacyEncryptorProvider,
   state: SomeStateProvider,
   log: disabledSemanticLoggerProvider,
+  now: () => 100,
 };
 
 function fooMaxLength(maxLength: number): StateConstraints<TestType> {

libs/common/src/tools/state/user-state-subject.ts

@@ -477,7 +477,12 @@ export class UserStateSubject<
    * @returns the subscription
    */
   subscribe(observer?: Partial<Observer<State>> | ((value: State) => void) | null): Subscription {
-    return this.output.pipe(map((wc) => wc.state)).subscribe(observer);
+    return this.output
+      .pipe(
+        map((wc) => wc.state),
+        distinctUntilChanged(),
+      )
+      .subscribe(observer);
   }
 
   // using subjects to ensure the right semantics are followed;