[moetemp]

What changed?

This PR adds the client target to the TypeScript generator, with the @nexus.poll iterator of temporalio#325.

• With --targets workflow,client, the output gets a client/ package. It has a client extension mixin per service, its own resource classes and get<Resource>.
• A client class implements createNexusClient, which can return client.nexus.createServiceClient(options). A client resource takes that service-bound client first, and each call uses a new random operation ID.
• @nexus.poll with a typescript helper gives iter<Name>.
• A proto-bound 64-bit value of a client resource is Long, as in fix(typescript): infer Long from protobuf resource bindings temporalio/nexgen#345.
• Output without the Workflow target writes each resource with its fields only, since its resources.ts imported operation files that it didn't write.

Why?

The Python client target of temporalio#344 has no TypeScript half.

How did you test it?

Link to a test plan if any -

• Unit Tests
• Staging
• End to End Tests

stream-client.test.ts checks a create, a rebuilt handle and the read loop with a fake client. tsc checks it and the stream output.