Make odsp test cache less likely to fail (microsoft#22585)

[AB#15994](https://dev.azure.com/fluidframework/235294da-091d-4c29-84fc-cdfc3d90890b/_workitems/edit/15994)

Looking at the errors, it only looks like this occurred once. Based on
the error stack, I've made some improvements to the `TestSnapshotCache`
so that the persisted cache can be used for other non-snapshot storage,
and non-`ValueWithSnapshot` types can be stored.

packages/test/test-end-to-end-tests/src/testSnapshotCache.ts

@@ -16,16 +16,19 @@ export interface ValueWithSnapshot {
 }
 
 export class TestSnapshotCache implements IPersistedCache {
-	private readonly cache = new Map<string, ValueWithSnapshot>();
+	private readonly cache = new Map<string, unknown>();
 	private readonly versionCache = new Map<string, ValueWithSnapshot>();
 	private readonly versionToCacheKey = new Map<string, string>();
-	public async get(entry: ICacheEntry): Promise<ValueWithSnapshot | undefined> {
+	public async get(entry: ICacheEntry): Promise<any | undefined> {
 		const key = getKeyForCacheEntry(entry);
 		return this.cache.get(key);
 	}
-	public async put(entry: ICacheEntry, value: ValueWithSnapshot): Promise<void> {
+	public async put(entry: ICacheEntry, value: any): Promise<void> {
 		const key = getKeyForCacheEntry(entry);
 		this.cache.set(key, value);
+		if (value.value?.snapshotTree?.id === undefined) {
+			return;
+		}
 		const versionKey = `${value.value.snapshotTree.id}`;
 		this.versionCache.set(versionKey, value);
 		this.versionToCacheKey.set(versionKey, key);