Add volar support for vue (#3992)

* feat-draft: inital volar setup

* feat(volar): add documentation

* feat(volar): include default init opts

* feat(volar): add initial tests

* fix(volar): add possible project roots

* fix(volar): tests - use empty files

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

@@ -620,6 +620,7 @@ Notes:
   * `cspell`
   * `prettier`
   * `vls`
+  * `volar`
 * XHTML
   * `alex`
   * `cspell`

doc/ale-vue.txt

@@ -33,5 +33,36 @@ g:ale_vue_vls_use_global                             *g:ale_vue_vls_use_global*
   See |ale-integrations-local-executables|
 
 
+===============================================================================
+volar                                                           *ale-vue-volar*
+
+  It is required to have typescript installed in your project as your dev
+  dependency: `npm i -D typescript`
+
+g:ale_vue_volar_executable                         *g:ale_vue_volar_executable*
+                                                   *b:ale_vue_volar_executable*
+  Type: |String|
+  Default: `'volar-server'`
+
+  See |ale-integrations-local-executables|
+
+
+g:ale_vue_volar_use_global                         *g:ale_vue_volar_use_global*
+                                                   *b:ale_vue_volar_use_global*
+  Type: |Number|
+  Default: `get(g:, 'ale_use_global_executables', 0)`
+
+  See |ale-integrations-local-executables|
+
+
+g:vue_volar_init_options                         *g:ale_vue_volar_init_options*
+                                                 *b:ale_vue_volar_init_options*
+  Type: |Dictionary|
+  Default: `{ ... }`
+
+  Default is too long to show here, take a look at it over
+  `ale_linters/vue/volar.vim`
+
+
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale.txt

@@ -3168,6 +3168,7 @@ documented in additional help files.
     cspell................................|ale-vue-cspell|
     prettier..............................|ale-vue-prettier|
     vls...................................|ale-vue-vls|
+    volar.................................|ale-vue-volar|
   xhtml...................................|ale-xhtml-options|
     cspell................................|ale-xhtml-cspell|
     write-good............................|ale-xhtml-write-good|