Make guest username, uid, home directory configurable #6156

Job	Run time
Integration tests	6m 22s
Colima (v0.6.5)	7m 20s
Integration tests (on Linux) (alpine.yaml)	6m 12s
Lints	3m 18s
Integration tests (on Linux) (debian.yaml)	6m 26s
Integration tests (on Linux) (fedora.yaml)	7m 1s
Spell check	9s
Integration tests (on Linux) (archlinux.yaml)	7m 37s
Integration tests (on Linux) (opensuse.yaml)	7m 18s
Unit tests (1.22.x)	34s
Integration tests (on Linux) (docker.yaml)	18m 12s
Unit tests (1.23.x)	58s
Integration tests (on Linux) (../hack/test-templates/alpine-iso-9p-writable.yaml)	6m 3s
Integration tests (on Linux) (../hack/test-templates/net-user-v2.yaml)	7m 33s
Upgrade test (v0.15.1)	16m 6s
Integration tests (on Linux) (../hack/test-templates/test-misc.yaml)	16m 18s
VMNet test	10m 10s
vz (default.yaml)	9m 11s
vz (fedora.yaml)	12m 32s
Windows tests	3m 36s
	2h 32m 56s

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