feat(vim): add completion source name to completion menu

We have the kind of the completion item in the menu as an icon and the
name at the end. Now the end one has been replaced with the source name
so we can see what the completion item is and where it is from.

site-modules/core/files/vim/plugin/completion.lua

@@ -81,7 +81,7 @@ cmp.setup({
         end
 
         vim_item.menu = icons[vim_item.kind] or " "
-        vim_item.kind = "(" .. vim_item.kind .. ")"
+        vim_item.kind = "(" .. entry.source.name .. ")"
         return vim_item
       end,
     },