feat: multi selection. Only integrates with send_selected_to_qflist (#551)

This will not yet work with select actions. More work is needed in that case.

Co-authored-by: Simon Hauser <Simon-Hauser@outlook.de>

scripts/gendocs.lua

@@ -11,6 +11,7 @@ docs.test = function()
     "./lua/telescope/init.lua",
     "./lua/telescope/builtin/init.lua",
     "./lua/telescope/pickers/layout_strategies.lua",
+    "./lua/telescope/actions/init.lua",
   }
 
   table.sort(input_files, function(a, b)