Support builtins like __ERROR(CustomError) or __FUNC_SIG(FunctionSig)

[Mouradif]

First off, I can't say how grateful I am for you making this plugin. I was doing my stack comments manually so far and as you imagine it's very frustrating. I've been using this plugin for less than 24h but I can already observe a 100% increase in productivity 😄

I noticed that when using bulit-ins the stack comment isn't affected, it would be great to have support for these

Before:

  __ERROR(OnlyOwner)            // []

after

  __ERROR(OnlyOwner)            // [OnlyOwner]

or better yet, hash the signature directly

  __ERROR(OnlyOwner)            // [0x5fc483c5...]

(with ... to signify that it is right-padded)