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/button.cpp

@@ -44,7 +44,7 @@ std::string Button::getVKeyString() {
         case 0x0C:
             return "Clear";
         case 0x0D:
-            return "Enter";
+            return "Enter/Return";
         case 0x10:
             return "Shift";
         case 0x11:
@@ -183,37 +183,37 @@ std::string Button::getVKeyString() {
         case 0x5D:
             return "Apps";
         case 0x60:
-            return "Num 0";
+            return "Numpad 0";
         case 0x61:
-            return "Num 1";
+            return "Numpad 1";
         case 0x62:
-            return "Num 2";
+            return "Numpad 2";
         case 0x63:
-            return "Num 3";
+            return "Numpad 3";
         case 0x64:
-            return "Num 4";
+            return "Numpad 4";
         case 0x65:
-            return "Num 5";
+            return "Numpad 5";
         case 0x66:
-            return "Num 6";
+            return "Numpad 6";
         case 0x67:
-            return "Num 7";
+            return "Numpad 7";
         case 0x68:
-            return "Num 8";
+            return "Numpad 8";
         case 0x69:
-            return "Num 9";
+            return "Numpad 9";
         case 0x6A:
-            return "*";
+            return "Numpad *";
         case 0x6B:
-            return "+";
+            return "Numpad +";
         case 0x6C:
-            return "Seperator";
+            return "Numpad Seperator";
         case 0x6D:
-            return "-";
+            return "Numpad -";
         case 0x6E:
-            return ".";
+            return "Numpad .";
         case 0x6F:
-            return "/";
+            return "Numpad /";
         case 0x70:
             return "F1";
         case 0x71: