TypeScript support for Polyglot target

[hokeun]

Below is a list of subtasks to enable TypeScript support for the Polyglot target:

• Protobuf serialization for federated LF programs for the TypeScript target.
• LF code generator (lfc) support for including the TypeScript target for the Polyglot target.
• Support for decentralized coordination for the TypeScript target (this is not mandatory if we decide to only support centralized coordination when there is any federate in the TypeScript target; i.e., decentralized coordination support for the Polyglot target is only enabled when there is no TypeScript federate).
• Test LF programs including the TypeScript federates.
• Documentation for the TypeScript support in Polyglot LF programs and the decentralized coordination support for the TypeScript target.