Add naga linter for WGSL support (#4047)

* Add WGSL support using `naga` command

* Add documents for wgsl

* Add test for `naga` linter

* Separate naga handler callback to hanlder/naga.vim

autoload/ale/handlers/naga.vim

@@ -0,0 +1,30 @@
+" Author: rhysd <https://github.com/rhysd>
+" Description: Handle errors for naga-cli.
+
+function! ale#handlers#naga#Handle(buffer, lines) abort
+    let l:errors = []
+    let l:current_error = v:null
+
+    for l:line in a:lines
+        if l:line =~# '^error: '
+            let l:text = l:line[7:]
+            let l:current_error = { 'text': l:text, 'type': 'E' }
+            continue
+        endif
+
+        if l:current_error isnot v:null
+            let l:matches = matchlist(l:line, '\v:(\d+):(\d+)$')
+
+            if !empty(l:matches)
+                let l:current_error.lnum = str2nr(l:matches[1])
+                let l:current_error.col = str2nr(l:matches[2])
+                call add(l:errors, l:current_error)
+                let l:current_error = v:null
+                continue
+            endif
+        endif
+    endfor
+
+    return l:errors
+endfunction
+