Reimplement generator for aws-sdk

[ksss]

What

Merge ksss/aws-sdk-rbs-generator

As discussed in #110, I was preparing a big change about the generator for aws-sdk.
This is ksss/aws-sdk-rbs-generator.
This is a generator that completely replaces the generators/aws-sdk.

This PR add new generator in generators/aws-sdk-rbs-generator.
And delete generators/aws-sdk.

Why

Support Client#wait_until

Added support for Client#wait_until, which is a method that outputs differently depending on the argument.

Support Resource classes

This change will allow us to generate signatures for the resource class as well as the traditional client class.
The resource class is, for example, the Aws::S3::Resource class.

resource = Aws::S3::Resource.new
obj = resource.bucket('a').object('b')
#=> We will be able to check that obj is an instance of Aws::S3::Object !

How to operate

The generator will always overwrite and regenerate the target file.

Whenever an auto-generated file needs to be modified, the generator needs to be modified.

For classes that are not auto-generated, simply place the files under gems/aws-sdk-*/. This process is exactly the same as aws-sdk-ruby.

[pocke]

Thanks 🚀