Add eslint formatter

[academo]

Adds eslint --fix as a formatter

[creativenull]

Could you be able to rename the file to eslint_fmt.lua instead along with the sourceName key too?

I decided to add a convention to suffix a _fmt to CLI tools that also provide formatting capabilities, just to keep it unique from the linter source name.

Outside of that, this is good! Once you've renamed them I can merge it

[academo]

@creativenull there you go