Generated code does not comply with dartfmt standards

After generating dart files, said files are not compliant with dartfmt standards. This has the effect of causing builds to fail (several package developers require proper formatting in order to contribute) as well as significant score deductions employed by dart.dev itself when an author publishes a package that includes files generated by this library.

The gRPC lib should either run dartfmt or natively generate compliant code in order to avoid significant problems for authors that may choose to use this lib.