Allow Manifest V2 usage of session sync

Expands use of SessionSyncer to all Subject types. Correctly handles
replay buffer for each type to ignore the flood of data upon
subscription to each Subject type.

libs/angular/test-utils.ts

@@ -0,0 +1,3 @@
+export async function awaitAsync(ms = 0) {
+  await new Promise((resolve) => setTimeout(resolve, ms));
+}