Add stylua fixer for lua (#3789)

doc/ale-lua.txt

@@ -46,5 +46,25 @@ g:ale_lua_luafmt_options                             *g:ale_lua_luafmt_options*
   Default: `''`
 
   This variable can be set to pass additional options to the luafmt fixer.
+
+
+===============================================================================
+stylua                                                         *ale-lua-stylua*
+
+g:ale_lua_stylua_executable                       *g:ale_lua_stylua_executable*
+                                                  *b:ale_lua_stylua_executable*
+  Type: |String|
+  Default: `'stylua'`
+
+  This variable can be set to use a different executable for stylua.
+
+g:ale_lua_stylua_options                             *g:ale_lua_stylua_options*
+                                                     *b:ale_lua_stylua_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be set to pass additional options to the stylua fixer.
+
+
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale-supported-languages-and-tools.txt

@@ -288,6 +288,7 @@ Notes:
   * `luac`
   * `luacheck`
   * `luafmt`
+  * `stylua`
 * Mail
   * `alex`!!
   * `languagetool`!!

doc/ale.txt

@@ -2843,6 +2843,7 @@ documented in additional help files.
     luac..................................|ale-lua-luac|
     luacheck..............................|ale-lua-luacheck|
     luafmt................................|ale-lua-luafmt|
+    stylua................................|ale-lua-stylua|
   markdown................................|ale-markdown-options|
     markdownlint..........................|ale-markdown-markdownlint|
     mdl...................................|ale-markdown-mdl|