ci: add multi-artifact build #627

Job	Run time
Build and package cores	2m 2s
Split off ${{ matrix.artifact }}	0s
verify-core	4s
Test ${{ matrix.subarch }}:${{ matrix.board }}	0s
Publish jsons	0s
Collect logs	0s
cleanup-artifacts	3s
Publish core	0s
Build and package cores	9m 1s
Split off zephyr	8s
Split off zephyr_main	13s
Split off zephyr_unoq	6s
Split off zephyr_contrib	22s
Test zephyr:unoq	2m 44s
Test zephyr_main:portentah7	2m 46s
Test zephyr_main:niclasense	2m 50s
Test zephyr_main:giga	2m 51s
Test zephyr_main:portentac33	2m 50s
Test zephyr_contrib:frdm_mcxn947	2m 37s
Test zephyr_contrib:frdm_rw612	2m 36s
Test zephyr_contrib:ek_ra8d1	2m 40s
Test zephyr_main:opta	2m 50s
Test zephyr_main:nano33ble	2m 40s
Collect logs	8s
Publish jsons	6s
verify-core	0s
Publish core	0s
cleanup-artifacts	3s
	39m 40s

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