feat(ft): add haxe support (#362)

Doc: https://haxe.org/manual/introduction-hello-world.html

Author: tong

lua/Comment/ft.lua

@@ -77,6 +77,7 @@ local L = setmetatable({
     groovy = { M.cxx_l, M.cxx_b },
     handlebars = { M.handlebars, M.handlebars },
     haskell = { M.dash, M.haskell_b },
+    haxe = { M.cxx_l, M.cxx_b },
     heex = { M.html, M.html },
     html = { M.html, M.html },
     htmldjango = { M.html, M.html },