closure compiler warns in generated .ngfactory.ts files:
```
WARNING - property createInternal already defined on superclass module$contents$..$core$src$linker$ng_module_factory_NgModuleInjector; use @override to override it
```
PR Close#16137
Inlcuded fixes:
- include preamble in generated source map
- always add a mapping for line/col 0 so that the
generated sourcemap is not sparse
- use a uniue sourceUrl for inline templates even
in the AOT case