Expose gRPC compression options

[Sushisource]

Summary

• expose gRPC compression as concrete option variants on client connection options
• keep gzip as the default while allowing Temporalio::Client::Connection::GrpcCompressionOptions::None.new to opt out
• model the public/RBS types so future variants can add variant-specific fields, e.g. a zstd class with a level, without adding level to gzip

Testing

• bundle exec rubocop
• ruby -c temporalio/lib/temporalio/client.rb
• ruby -c temporalio/lib/temporalio/client/connection.rb
• ruby -c temporalio/test/client_test.rb