Update generated service and client class names to better handle well-named services.

[darronschall]

This PR follows #91 and subsequent discussions.

When a service is well-named and ends in "Service", such as "MessagesService", the generator generates class MessagesServiceService < Twirp::Serivice and class MessagesServiceClient < Twirp::Client.

This change causes the generator to generate class MessagesService < Twirp::Serivice and class MessagesClient < Twirp::Client instead.

The service name passed to the service DSL is not impacted (which was the problem in #91 that needed a revert).

For backwards compatibility, this change does not impact the current hello_world example, as demonstrated by:

# Check out and build the generator using updates from the this branch
$ git checkout service-class-name-suffix-fix
$ cd ./protoc-gen-twirp_ruby 
$ go build
$ go install

# Run code gen
$ cd ../example 
$ protoc --proto_path=. ./hello_world/service.proto --ruby_out=. --twirp_ruby_out=.

# Demonstrate no changes for services not already well-named
$ git status
On branch service-class-name-suffix-fix
Your branch is up to date with 'origin/service-class-name-suffix-fix'.

nothing to commit, working tree clean

I'm not familiar enough with go and testing to write tests for this in main_test.go. Any help there is appreciated.

[darronschall]

@arthurnn Should I also update names in test to be well-named, like #91 did in 8125bf0? Separate PR maybe?

[arthurnn]

thanks @darronschall , I have this on my schedule to test against some local projects. At first glance it looks good.
I will give it a final look by next week and let you know.

thanks again for the contribution.

[arthurnn]

I am putting a pin on this until I figure out what to do about the latest version hiccups. see #99.

thanks, and I added this back to my backlog to review by the end of the week

[darronschall]

@arthurnn Just wanted to check in since it's been a few months. Have you been able to take a look at this yet? No rush, and no pressure. It'd be nice to land this at some point.

[danielmorrison]

@arthurnn any chance we can get some eyes on this? It continues to be an annoyance for us.

Happy to assist with review and/or maintenance if it'd help.

[tiwilliam]

This would be a nice improvement. We run in to these when trying to respect service name lint rules.

[danielmorrison]

To clarify the problem again, when I have a service that ends in Service, it ends up duplicating the word Service in my _twirp.rb generated file:

service MessagesService {

class MessagesServiceService < ::Twirp::Service