Treat numpad-enter and enter keys as different

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> I'd like to bring across some keybindings from another editor. In those bindings I use the numpad enter key to trigger functions different from the main enter/return key. In VSCode the two keys are treated as one. I believe that all three platforms supported by VSCode have underlying keycodes and libraries that can distinguish the two keys.