Add concept of state overlays #2025

Job	Run time
Build (Fedora)	1m 15s
build-integration	4m 6s
Build - FCOS minimal	1m 40s
Code style	42s
Build (C9S)	1m 52s
Debian Stable with sign-ed25519 and FUSE 2	7m 40s
Debian Stable with curl, sign-ed25519, no gpgme, FUSE 3	7m 18s
Debian Stable 32 bit	7m 51s
Debian Stable without libsystemd	7m 21s
Debian Testing	8m 12s
Debian Testing with libsoup3	7m 2s
Debian stable + static-prepareroot	7m 39s
Ubuntu Latest Release	8m 24s
Privileged testing	2m 20s
	1h 13m 22s

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