Add tracing with the tracing crate

[MarcGuiselin]

Debugging the beast that is the Polywrap ecosystem is frankly quite a pain.

It's difficult to track down what happens when invoking a wrap. There should be events logged at all steps: resolution, fetching wraps, invocation, sub-invocation etc.

Since sub-invokes can go quite deep, a crate like tracing-tree can help by visualizing the tree of invokes.

A nice to have feature would be for the client to also log parsed (human readable) invoke params and responses sent between wraps when tracing is enabled.