Bootloader for CI device tests

This bootloader always runs into bootloader mode, waits for firmware to be uploaded, then runs the firmware.

Storage is not erased. If you wish to erase storage, do it inside your test.

All user interaction is removed (no clicking or confirmations required) so that it can be used in an automated way for tests.

The bootloader will run any firmware that looks "sane" (good header, hashes), but does not check any trust flags.

Firmware must be compiled with PRODUCTION=0 because otherwise it would replace the bootloader and lock device.