Added ruby wrapper for grpc_compression_options

src/ruby/ext/grpc/rb_compression_options.c

src/ruby/ext/grpc/rb_compression_options.h

src/ruby/ext/grpc/rb_grpc.c

src/ruby/lib/grpc.rb

src/ruby/lib/grpc/core/compression_options.rb

src/ruby/spec/compression_options_spec.rb