fix: return null ls setup user config (#1683)

lua/lsp/config.lua

@@ -21,4 +21,7 @@ return {
   on_attach_callback = nil,
   on_init_callback = nil,
   automatic_servers_installation = true,
+  null_ls = {
+    setup = {},
+  },
 }

lua/lsp/null-ls/init.lua

@@ -12,7 +12,7 @@ function M:setup()
   end
 
   null_ls.config()
-  require("lspconfig")["null-ls"].setup {}
+  require("lspconfig")["null-ls"].setup(lvim.lsp.null_ls.setup)
   for _, filetype in pairs(lvim.lang) do
     if filetype.formatters then
       formatters.setup(filetype.formatters, filetype)