soc: espressif: Simple boot support

Add simplistic booting method which allows to load without 2nd stage
bootloader.
Update common architecture loader to support all build scenarios.

- simple boot: using single binary application without bootloader
- mcuboot: zephyr port of MCUboot
- application: loaded by the MCUboot

Signed-off-by: Marek Matej <marek.matej@espressif.com>