Implement naming conventions in Go grammar

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Description of the Change

This is a rewrite of the Tree-sitter grammar to implement naming conventions for syntax scopes.

Benefits

• Many new scopes added to make the grammar explicit and exhaustive.
• Notable improvements on punctuation and types.
• Highlighting to be consistent with other languages.

Possible Drawbacks

Some new scopes to be added to themes. The changes aim to facilitate theme development, filling the template is enough to ensure coherent highlighting across languages, instead of painfully creating styling rules for every language separately.

Applicable Issues

• There is no naming convention of scope selectors atom#8430

Related Pull Requests

• Naming conventions documentation
• Implementation in template theme
• Implementation in default syntax themes
• Implementation in C and C++ grammars
• Implementation in CSS grammar
• Implementation in HTML grammar
• Implementation in JavaScript and Regex grammars
• Implementation in Python grammar
• Implementation in Ruby grammar

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Preview of the changes with Atom's default syntax themes:

Without naming conventions (current Tree-sitter grammar)	With naming conventions in theme and Tree-sitter grammar
Solarized Dark	Solarized Dark
One Dark	One Dark
Base16 Tomorrow Dark	Base16 Tomorrow Dark
Atom Dark	Atom Dark
Solarized Light	Solarized Light
One Light	One Light
Base16 Tomorrow Light	Base16 Tomorrow Light
Atom Light	Atom Light

Code snippet:

package main

import (
  "bosco"
  mule "molly"
)

// Management will be pleased

const pet string = "steeve"

func dig(b *Bag, i int) int {
  b.bismor += i
  return molly.come.here()
}

type Bag struct {
  gold, nitra, bismor int
}

func yell(say func(string)) {
  say("For Karl")
  say("Rock & Stone")
}

func main() {

  var inventory Bag
  var iron, will = true, true
  var core interface{} = 1.4
  var matrix = &core
  const leaf_lover = iota * 2

  beers := map[string]int{
    "Dark Morkite": 5,
    "Malt Rockbearer": 4,
  }

  laser := make(chan string)
  go func() {
    laser <- "jadiz"
  }()
  look_here := <-laser

  flares := []int{2, 3, 4}
  for i, f := range flares {
    if f >= 4 {
      say("Out of flares")
    } else {
      say("Lighting up")
    }
  }
}