incus/storage: Add yaml support for storage create #1667

Job	Run time
Documentation	6m 17s
Code	6m 37s
Client (1.21.x, ubuntu-latest)	1m 21s
Client (1.21.x, macos-latest)	2m 1s
Client (1.21.x, windows-latest)	1m 33s
System (1.21.x, cluster, dir)	12m 46s
System (1.21.x, cluster, btrfs)	3m 3s
System (1.21.x, cluster, lvm)	12m 27s
System (1.21.x, cluster, zfs)	11m 54s
System (1.21.x, cluster, ceph)	15m 30s
System (1.21.x, cluster, random)	11m 38s
System (1.21.x, standalone, dir)	20m 54s
System (1.21.x, standalone, btrfs)	21m 4s
System (1.21.x, standalone, lvm)	39m 14s
System (1.21.x, standalone, zfs)	38m 43s
System (1.21.x, standalone, ceph)	1h 14m 13s
System (1.21.x, standalone, random)	34m 28s
System (stable, cluster, dir)	10m 50s
System (stable, standalone, dir)	20m 33s
System (tip, cluster, dir)	12m 24s
System (tip, standalone, dir)	21m 35s
	6h 19m 5s

Provide feedback