#23 - Add source comments from file descriptor

[n3rdyme]

Added comments from fileDescriptor.sourceCodeInfo to enums, message interfaces, and services.

Should resolve issue 23
#23

[stephenh]

This looks really great!

Made a few stylistic asks/questions, but overall is great.

Can you add some comments to the simple.proto-type files that are used for ts-proto's test suite, and then in theory we should be able to see some example-generated comments in the PR (b/c the code generated for the proto/integration tests is purposefully checked in to see these sort of changes in the diffs). I could also try that if the test suite setup is too jank (it's not just npm test), but their is an overview in the readme that hopefully works. Let me know if it doesn't / you don't have time, and I'll throw in a few example comments to see what the output looks like before merging.

[n3rdyme]

@stephenh
I added the requested comments in simple.proto and cleaned up the conditional logic a bit. I assume you did not want me to regenerate all the binary and source files on branch. It seems like that might make merging difficult, so I assume you are keeping PR branches clean?

Otherwise, I think I covered all the asks above. Let me know if you need any additional changes.

[stephenh]

Looks great, thanks! I do actually check in the generated source files; I know in downstream / real projects that is an anti-pattern but given ts-proto's job is producing that output, I basically treat it as an mini-integration test to see how the output has changed in the PRs/diffs/etc. I'll go ahead and do a follow up commit with those changes now.