Support arguments when defining keybindings

[bpasero]

Allow to pass arguments to commands defined in keybindings.json.

/cc @alexandrudima not sure if you have an existing item for this already?

[bpasero]

@alexandrudima currently I am not showing args in IntelliSense so this feature is a bit hard to learn as a new user unless you maybe check the documentation. But I also worry that it is such a corner case that it maybe would be advertised too prominently. Any ideas how to make this discoverable?

[alexdima]

@bpasero At one point we will migrate to a single move command. ie. cursorLeft, cursorRight, etc. will all point to one command and pass in different args. It shall then become discoverable :)