Add CI coverage for nRF5340 plus nRF21540 FEM usage in
hci_uart plus hci_ipc samples.
The overlay values are inspired from:
https://github.com/nrfconnect/sdk-nrf/tree/
85307a9ca0fb6ba8c61f4bd05b7f866cde42612f/boards/shields/nrf21540ek
Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>