[Backport ncs-v3.1-branch] [nrf fromlist] cmake: mcuboot: SHA512/pure image signing#3165

carlescufi merged 2 commits intoncs-v3.1-branchnrfconnect/sdk-zephyr:ncs-v3.1-branchfrom

backport-3074-to-ncs-v3.1-branchnrfconnect/sdk-zephyr:backport-3074-to-ncs-v3.1-branchCopy head branch name to clipboard