[FEATURE] `wash spy`

[thomastaylor312]

To help users debug and understand their applications, we need an easy way for them to see what is going on. We should add a command to wash that allows a user to specify an actor (not by ID) and then wash automatically subs on the correct invocation topics and decodes msgpack for them

It could look kinda like this

$ wash spy echo
Listening for echo invocations

[TIMESTAMP] { method: "GET", body: [data] ...}

As part of this, we should add an "experimental" env var and flag that let's people turn on experiments like this one. This feels like an "easy win" feature but locks it behind a flag in case we change or remove it