overlay: "reset all" buttons for buttons/overlay/analog tabs (#578)

## Link to GitHub Issue or related Pull Request, if one exists
#576 

## Description of change
Add `Reset All` buttons to these tabs which clears out bindings to none
/ default.

For keypads, introduce a special `Use Preset` button which lets users
pick between numpad and top row number keys.

Update UI-visible string used for vKeys, especially the numpad ones
(e.g., `.` is now `Numpad .` to distinguish from the regular `.`
period).

Breaking change: if the user never had `P1 Keypad 00` set, the default
will change from `Enter` to `Numpad -` since both enter keys trigger the
same. This will affect a small number of popn/ddr players. They can just
change it back.

## Testing
*how was the code tested?*

src/spice2x/cfg/api.cpp

@@ -37,7 +37,11 @@ std::vector<Button> GameAPI::Buttons::sortButtons(
         for (auto &bt : buttons) {
             if (name == bt.getName()) {
                 button_found = true;
-                sorted.push_back(bt);
+                Button button_new = bt;
+                if (vkey_defaults) {
+                    button_new.setVKeyDefault(vkey_defaults->at(index));
+                }
+                sorted.push_back(button_new);
                 break;
             }
         }
@@ -47,6 +51,7 @@ std::vector<Button> GameAPI::Buttons::sortButtons(
 
             if (vkey_defaults) {
                 button.setVKey(vkey_defaults->at(index));
+                button.setVKeyDefault(vkey_defaults->at(index));
             }
         }