Removes:
* AUTORESET_DELAY_MS which never did anything but was introduced
somehow.
* CIRCUITPY_BOOT_BUTTON in all but one ESP board because they all have
them. There is a default based on the strapping pins.
* BOARD_USER_SAFE_MODE_ACTION because it was all the same for boards
with boot buttons. Now the safe mode code manages the message.
Dan Halbert
Jeff Epler
Scott Shawcroft
Fabian Affolter