Add option to supress file extension

[jsumners]

It would be fantastic if this extension had an option to suppress filename extensions upon completion.

Instead of completing to:

const foo = require('./lib/foo.js')

Complete to:

const foo = require('./lib/foo')

[duro]

@Jerry-Hong It seems that the "autofilename.extensions.trim" setting was intended to solve this, but it does not seem to be working for me. I have it setup like this:

"autofilename.extensions.trim": ["js"]

But it does not strip off the .js from the auto completed file