Re-synthesize line number for unresolved metadata build errors

[leonsenft]

When an argument to directives can't be resolved, in this example because of a missing import,

import 'package:angular/angular.dart';

@Component(
  selector: 'app',
  template: 'Hello world',
  directives: const [FooDirective],
)
class AppComponent {}

we emit a build failure indicating which argument couldn't be resolved with incorrect line and column information

[SEVERE]: Compiling @Component-annotated class "AppComponent" failed.

Try the following when diagnosing the problem:
  * Check your IDE or with the dartanalyzer for errors or warnings
  * Check your "import" statements for missing or incorrect URLs

If you are still stuck, file an issue and include this error message:
https://github.com/dart-lang/angular/issues/new

line 1, column 121 of package:example/app_component.dart: This argument *may* have not been resolved
FooDirective
^^^^^^^^^^^^

The column number is actually the character offset into the file at which the argument occurs, and should be used to re-synthesize the correct line and column numbers.

[matanlurey]

/cc @MichaelRFairhurst - this is something we might need help with.