Dynamic switching between ESP32 and ARM based boards (Possibly Nordic as well)

[0Grit]

@ramb0t asked about how to build a single application for various chipsets with only a single Zephyr workspace.

• ESP32
• STM32
• Possibly Nordic but NCS makes this complicated

We can keep this discussion as a way to track progress towards this ideal scenario.
@mniestroj @alvarowolfx