Factor out connection, peer management, and packet handling into VideoCallClient

[ronen]

[Continuing down the path of #74]

This PR create a single VideoCallClient interface that internally takes care of the connection, packet handling, encryption, peer management, etc. -- moving all that code out of the Attendants and Host components.

Part of that cleanup included changing the encoders so that they too use the VideoCallClient in their interfaces

[ronen]

But oh darn, I just tested e2ee (again) and it's not working now. So hold off on committing this, I need to debug.

[ronen]

Hey, sorry for the long delay -- got distracted by my day job.

I've pushed a commit that fixed the problem, by replacing "callback hell" with a more straightforward approach for handling new peers. And did some code cleanup along the way (those went hand-in-hand :)

Then while I was in a code cleaning mood I tidied up a few other things in the client & peer_decoder_manager, in a few other commits.

Should be good to go now!

[darioalessandro]

lgtm!!!!

[darioalessandro]

I took a stab at rebasing this myself but it is not trivial!

[ronen]

Hey @darioalessandro, @griffobeid any thoughts about how to handle the UI test suite failure?

It seems to be due to wasm-bindgen versionitis.

...and seems unrelated to my having just merged in main and resolved the conflicts? 🤷🏻

[darioalessandro]

I think that @griffobeid is looking into this

[griffobeid]

@ronen @darioalessandro Yeah it is a version mismatch.

After doing

cargo install -f wasm-bindgen-cli --version 0.2.87

Tests are passing just fine, don't worry about it with your changes I can clean this up