Add // coverage:ignore-file to the header of the generated files to ignore for code coverage

[ghost]

Currently the header of a generated file looks like:

/// // Generated code. Do not modify. // source: geometry.proto // // @dart = 2.12 // ignore_for_file: annotate_overrides,camel_case_types,unnecessary_const,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type,unnecessary_this,prefer_final_fields
It would be great if it can be extended with:
// coverage:ignore-file

so that the generated file is ignored during code coverage analysis.
Thanks