These files are needed so that:
- user code can compile even without real codegen
- as tsc transformers cannot create but only change existing files
in the transformation pipeline.
This commit adds a new parameter to ngc named `missingTranslation` to set the MissingTranslationStrategy for AoT, it takes the value `error`, `warning` or `ignore`.
Fixes#15808
PR Close#15987
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
