Add JASS progamming language

[Drake53]

Add JASS, the Warcraft III scripting language.

Description

JASS is the original scripting language of Warcraft III.
It has been the World Editor's default output since 2002; Lua was added as an alternative in patch 1.31 (2019), but JASS remains what the editor emits unless a map opts into Lua, and it backs a large existing corpus of map scripts and hand-written libraries on GitHub.

Those .j files are currently either left unclassified or attributed to Jasmin or Objective-J, the two languages that share the .j extension.
This PR adds JASS with a syntax-highlighting grammar, four real-world samples, and a new .j heuristic that disambiguates all three languages.

Scope: JASS, not vJASS

This adds original JASS only. vJASS (JassHelper) is usually described as a superset of JASS, but it is not strictly one, so folding the two together would be wrong.
The clearest example is the debug keyword: in JASS debug applies to the entire statement that follows it, so it carries through a multi-line construct such as an if … endif block, whereas in vJASS it applies only to the line it appears on.
The same source text can therefore mean different things in the two languages.
The grammar and the samples here are plain JASS; no vJASS, Zinc or Wurst constructs are included.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.j+endfunction — 14k files
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/Drake53/War3Net/blob/master/tests/War3Net.TestTools.UnitTesting/TestData/MapFiles/TestGenerateUnitData/war3map.j
      • https://github.com/eGlint/Warcraft-III-Noise-Library/blob/master/JASS/Noise.j
      • https://github.com/eGlint/Warcraft-III-Noise-Library/blob/master/JASS/OctavePerlin.j
      • https://github.com/Son-Guhun/Titan-Land-Lands-of-Plenty/blob/master/release/trigger/41-Disable%20System%20-%20GDS/3-GDS%20Main.j
    • Sample license(s): MIT
  • I have included a syntax highlighting grammar: https://github.com/Drake53/language-jass
  • I have added a color
    • Hex value: #FF0303
    • Rationale: This is the color used by player 1 in Warcraft III. It's visually distinct from other languages that often share a repository with JASS (C#, lua, typescript).
  • I have updated the heuristics to distinguish my language from others using the same extension.