feat: revamp socket URL handling with currentScript source

[pmmmwh]

This fixes #105. It partially reverts changes in #106 because I was wrong about some assumptions on Webpack's __resourceQuery.

This change keeps IE11 compatibility for everyone other than WDS users (This is because, even if they polyfill URL, we will always run before the polyfill - unconfirmed though). All code with usage of the URL constructor is self-contained within WDSSocket.

Edit:
I've pulled the trigger to expand the scope of this.

Additional features resolves:
Fixes #30
Fixes #100

[pmmmwh]

Hmmmm this change will make further changes addressing resource query parsing much more difficult.

I was right in #106 about what I wanted to do - maybe I should just go ahead and handle #30 and #100 altogether ...