feat: introduce source maps for templates (#15011)

The main use case for the generated source maps is to give
errors a meaningful context in terms of the original source
that the user wrote.

Related changes that are included in this commit:

* renamed virtual folders used for jit:
  * ng://<module type>/module.ngfactory.js
  * ng://<module type>/<comp type>.ngfactory.js
  * ng://<module type>/<comp type>.html (for inline templates)
* error logging:
  * all errors that happen in templates are logged
    from the place of the nearest element.
  * instead of logging error messages and stacks separately,
    we log the actual error. This is needed so that browsers apply
    source maps to the stack correctly.
  * error type and error is logged as one log entry.

Note that long-stack-trace zone has a bug that 
disables source maps for stack traces,
see https://github.com/angular/zone.js/issues/661.

BREAKING CHANGE:

- DebugNode.source no more returns the source location of a node.  

Closes 14013

packages/compiler/testing/src/resource_loader_mock.ts

@@ -23,6 +23,8 @@ export class MockResourceLoader extends ResourceLoader {
     return request.getPromise();
   }
 
+  hasPendingRequests() { return !!this._requests.length; }
+
   /**
    * Add an expectation for the given URL. Incoming requests will be checked against
    * the next expectation (in FIFO order). The `verifyNoOutstandingExpectations` method