Streaming support for WASI HTTP incoming handler invocation

[vigoo]

After #1184 is done, the next step is to support streaming request bodies and response bodies.

This will require custom implementations of the WASI HostInputStream and HostOutputStream interfaces (there are already existing examples for doing that) that are somehow mapping to the open gRPC stream.

Challenges:

• Implement the WASI stream - gRPC stream mapping
• How to inject these custom stream implementations into the WASI HTTP incoming request / outgoing response host resources (may require changes in wasmtime's wasi-http implementation in our fork)
• Durability - the streaming support must not break durability guarantees, a worker that was interrupted / replayed in the middle of an incoming request handler must work as expected.

Make sure that as part of this ticket there are worker executor tests using streaming AND simualting worker restarts.