newt: Add external repos patches support #152

Job	Run time
populate-targets	5s
newt dump (bleprph-nrf52840pdk, ubuntu-latest)	19s
newt dump (bleprph-nrf52840pdk, windows-latest)	1m 22s
newt dump (bleprph-nrf52840pdk, macos-latest)	1m 2s
newt dump (boot-nrf52dk, ubuntu-latest)	26s
newt dump (boot-nrf52dk, windows-latest)	1m 21s
newt dump (boot-nrf52dk, macos-latest)	59s
newt dump (btshell-nrf52840pdk, ubuntu-latest)	21s
newt dump (btshell-nrf52840pdk, windows-latest)	1m 17s
newt dump (btshell-nrf52840pdk, macos-latest)	40s
newt dump (btshell-nrf52dk, ubuntu-latest)	22s
newt dump (btshell-nrf52dk, windows-latest)	1m 5s
newt dump (btshell-nrf52dk, macos-latest)	1m 3s
newt dump (my_blinky_sim, ubuntu-latest)	21s
newt dump (my_blinky_sim, windows-latest)	1m 5s
newt dump (my_blinky_sim, macos-latest)	59s
	12m 47s

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