resolve #1140 support folding ---@alias

Author: sumneko

changelog.md

@@ -4,6 +4,7 @@
 * `NEW` settings:
   + `workspace.supportScheme`: `["file", "untitled", "git"]`
   + `diagnostics.disableScheme`: `["git"]`
+* `NEW` folding: support folding `---@alias`
 * `FIX` hover: can not union `table` with other basic types
 * `FIX` [#1125](https://github.com/sumneko/lua-language-server/issues/1125)
 * `FIX` [#1131](https://github.com/sumneko/lua-language-server/issues/1131)

script/core/folding.lua

@@ -143,6 +143,15 @@ local care = {
         }
         results[#results+1] = folding
     end,
+    ['doc.alias'] = function (source, text, results)
+        local folding = {
+            start        = source.start,
+            finish       = source.bindGroup[#source.bindGroup].finish,
+            kind         = 'comment',
+            hideLastLine = true,
+        }
+        results[#results+1] = folding
+    end
 }
 
 ---@async