lang/lua: improve moonscript & love2D support

- Fix moonscript-mode not highlighting/treating single-quoted strings as
  strings
- Fontify interpolated expressions in moonscript-mode strings (PR
  upstream?)
- Fix +lua-love-mode project detection
- Fix +lua/run-love-game love project root resolution

modules/lang/lua/autoload/lua.el

@@ -0,0 +1,38 @@
+;;; lang/lua/autoload/lua.el -*- lexical-binding: t; -*-
+
+(defun +lua-love-build-command ()
+  (when-let (root (+lua-love-project-root))
+    (format "%s %s"
+            (if (executable-find "love")
+                "love"
+              (if IS-MAC "open -a love.app"))
+            (shell-quote-argument root))))
+
+;;;###autoload
+(defun +lua/open-repl ()
+  "Open Lua REPL."
+  (interactive)
+  (lua-start-process "lua" "lua")
+  (pop-to-buffer lua-process-buffer))
+
+;;;###autoload
+(defun +lua/run-love-game ()
+  "Run the current project with Love2D."
+  (interactive)
+  (if-let (cmd (+lua-love-build-command))
+      (async-shell-command cmd)
+    (user-error "Couldn't find love project")))
+
+;;;###autoload
+(defun +lua-love-project-root ()
+  "Returns the directory where a main.lua exists.
+
+Returns nil if 'love' executable can't be found."
+  (when (executable-find "love")
+    (or (and (projectile-locate-dominating-file default-directory "main.lua")
+             (when-let (root (projectile-locate-dominating-file default-directory "src/main.lua"))
+               (expand-file-name "src" root)))
+        (and (featurep! +moonscript)
+             (projectile-locate-dominating-file default-directory "main.moon")
+             (when-let (root (projectile-locate-dominating-file default-directory "src/main.moon"))
+               (expand-file-name "src" root))))))