fix(ivy): TestBed should not clobber compilation of global-scope modules (#28033)

When an @NgModule decorator executes, the module is added to a queue in
render3/jit/module.ts. Reading an ngComponentDef property causes this queue
to be flushed, ensuring that the component gets the correct module scope
applied.

In before_each.ts, a global beforeEach is added to all Angular tests which
calls TestBed.resetTestingModule() prior to running each test. This in turn
clears the module compilation queue (which is correct behavior, as modules
declared within the test should not leak outside of it via the queue).

So far this is okay. But before the first test runs, the module compilation
queue is full of modules declared in global scope. No definitions have been
read, so no flushes of the queue have been triggered. The global beforeEach
triggers a reset of the queue, aborting all of the in-progress global
compilation, breaking those classes when they're later used in tests.

This commit adds logic to TestBedRender3 to respect the state of the module
queue before the TestBed is first initialized or reset. The queue is flushed
prior to such an operation to ensure global compilation is allowed to finish
properly.

With this fix, a platform-server test now passes (previously the <my-child>
element was not detected as a component, because the encompassing module
never finished compilation.

FW-887 #resolve

PR Close #28033

packages/core/src/core_render3_private_export.ts

@@ -135,6 +135,7 @@ export {
   compileNgModuleDefs as ɵcompileNgModuleDefs,
   patchComponentDefWithScope as ɵpatchComponentDefWithScope,
   resetCompiledComponents as ɵresetCompiledComponents,
+  flushModuleScopingQueueAsMuchAsPossible as ɵflushModuleScopingQueueAsMuchAsPossible,
   transitiveScopesFor as ɵtransitiveScopesFor,
 } from './render3/jit/module';
 export {