grep_project: exclude filename from fuzzy search by default

lua/fzf-lua/providers/grep.lua

@@ -362,6 +362,11 @@ end
 M.grep_project = function(opts)
   if not opts then opts = {} end
   if not opts.search then opts.search = '' end
+  -- by default, do not include filename in search
+  if not opts.fzf_opts or opts.fzf_opts["--nth"] == nil then
+    opts.fzf_opts = opts.fzf_opts or {}
+    opts.fzf_opts["--nth"] = '2..'
+  end
   return M.grep(opts)
 end