[Feature Request] Ractor-based sandboxing

[cretz]

Describe the solution you'd like

Decide whether we even want Ractor-based sandboxing, then implement it.

This mostly works today except for Google::Protobuf (see protocolbuffers/protobuf#19321). But we have all these protos and impl in Rust, so it would not be that hard to make a method_missing version of this (which is effectively what the existing Ruby extension does at https://github.com/protocolbuffers/protobuf/tree/main/ruby/ext/google/protobuf_c), just effort and confirming we are ok abandoning the official proto library (which has other benefits such as not clashing with users' protobuf library use).

[cretz]

It has been decided that while there are a lot of state-isolation benefits to Ractor-based workflows, since Google::Protobuf doesn't support them and since they are experimental, it is not worth the effort to require them today. We can revisit when ecosystem support improves.