[Player] [Mobile] Make 'Undo' a repeatable button

Summary

Make the 'Undo' mobile button repeatable, so that you can undo several steps while keeping your finger on the button, instead of having to press-release-press-release-...

Details

In the player, while on mobile mode, there is a tab that you can open with three buttons: Undo, restart and Quit to menu:

Clicking these buttons makes the corresponding action as expected.

While the restart and quit are mostly idempotent (once pressed, next presses will probably not change the game state, so you will probably click them only once each time) the undo button on the other hand may be pressed several times in quick succession if you want to go back to a previous game state.

While on keyboard (or gamepad I guess) you can keep the button down and it will keep undoing repeatedly until you unpress, on mobile however this functionality doesn't exists, which means that you need to manually press the button each time you want to undo, which is often slow and tiring.
By making the undo button repeatable, you should be able to 'keep undoing' while the button is held, and stop once released. The rate of 'undoing' should be the same as the rate of moving if you swipe+hold.

Start at the player's mobile-mode tab and its Undo control, then compare its behavior with the keyboard/gamepad hold-to-repeat path and the swipe+hold movement rate. Done means holding Undo repeatedly undoes steps, releasing stops it, and the repeat rate matches swipe-and-hold movement.