Creating a JoypadApple can trigger a notification to add a joypad (if
a device is already connected before the game is started). Observed
on iOS 18.2.1 with a Nimbus SteelSeries.
However at this point the Input singleton is not available yet, so
it will crash.
This commit moves JoypadApple initialization to `initialize_joypad()`
which is called explicitly after the Input singleton is available.
This is consistent with other platform joypad initialization.
e77a011188