Change Sync to a prop instead of a positional argument

[kixelated]

Several APIs take Sync as the first positional argument rather than as a property in the options/props object:

const sync = new Watch.Sync();

// Currently: sync is first arg
const muxer = new Watch.Mse.Muxer(sync, { paused: false });
const videoSource = new Watch.Video.Source(sync, { broadcast });
const audioSource = new Watch.Audio.Source(sync, { broadcast });

It would be more consistent and ergonomic if sync were part of the props object:

const muxer = new Watch.Mse.Muxer({ sync, paused: false });
const videoSource = new Watch.Video.Source({ sync, broadcast });
const audioSource = new Watch.Audio.Source({ sync, broadcast });

This aligns with how other options like broadcast, paused, canvas etc. are already passed as props. Having sync as a separate positional argument is the odd one out.