(OL2) refactor read queue (#4948)

* Rename to saveBatch

* forgot a file

* first pass of cacheReader

* OL2 tests have infinite timeout

* OL2 refactor works

* fix for tests

* get rid of pumps and fix test

* lint fix

* redo mermaid diagrams

* add readme section on deferment

packages/objectloader2/src/helpers/cacheReader.spec.ts

@@ -11,7 +11,7 @@ describe('CacheReader testing', () => {
     const deferments = new DefermentManager({ maxSizeInMb: 1, ttlms: 1 })
     const cacheReader = new CacheReader(
       new MemoryDatabase({
-        items: new Map<string, Base>([[i1.baseId, i1.base]])
+        items: new Map<string, Base>([[i1.baseId, i1.base!]])
       }),
       deferments,
       {