Add a way to cache default keymaps, impl function for adding temporary

keymaps (i.e keymaps during debugging) which saves original keymaps if
it overrides them at restores them upon deletion.

home/.config/nvim/lua/plugs/nvim-dap.lua

@@ -79,7 +79,7 @@ return {
         local function enter_debug_mode()
             dapui.open()
             if not are_stepping_keymaps_active then
-                utils.add_keymaps(stepping_keymaps)
+                utils.add_temporary_keymaps(stepping_keymaps)
                 are_stepping_keymaps_active = true
             end