Add rootless support #893

Job	Run time
build-linux (containerd-system)	52s
context (ubuntu-latest)	33s
build-linux (containerd-tarball)	48s
channel (ubuntu-latest)	32s
context (macos-13)	5m 49s
context (windows-latest)	35s
daemon-config (ubuntu-latest)	28s
channel (macos-13)	7m 39s
daemon-config (macos-13)	8m 47s
channel (windows-latest)	28s
daemon-config (windows-latest)	40s
lima-start-args	10m 46s
main (ubuntu-latest, pinned)	32s
build-macos (macos-13)	14m 49s
build-windows	49s
main (ubuntu-latest, latest)	31s
build-macos (macos-12)	8m 39s
main (ubuntu-latest, type=image,tag=27.3.1)	30s
main (macos-13, pinned)	7m 7s
set-host	30s
main (macos-13, latest)	9m 17s
main (macos-13, type=image,tag=27.3.1)	3m 35s
main (windows-latest, pinned)	23s
main (windows-latest, latest)	30s
main (windows-latest, type=image,tag=27.3.1)	42s
	1h 25m 51s

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