Updates the module name in the idiomatic and stub layers

src/ruby/lib/grpc.rb

src/ruby/lib/grpc/auth/compute_engine.rb

src/ruby/lib/grpc/auth/service_account.rb

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

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

src/ruby/lib/grpc/errors.rb

src/ruby/lib/grpc/generic/active_call.rb

src/ruby/lib/grpc/generic/bidi_call.rb

src/ruby/lib/grpc/generic/client_stub.rb

src/ruby/lib/grpc/generic/rpc_desc.rb

src/ruby/lib/grpc/generic/rpc_server.rb

src/ruby/lib/grpc/generic/service.rb

src/ruby/lib/grpc/logconfig.rb

src/ruby/lib/grpc/version.rb

src/ruby/spec/auth/compute_engine_spec.rb

src/ruby/spec/auth/service_account_spec.rb