Add multi-site support to ubi crate #408

Job	Run time
FreeBSD-x86_64 with rust stable	35s
Linux-x86_64 with rust stable	33s
Linux-x86_64 (rustls-native-roots) with rust stable	40s
Alpine Linux	1m 35s
Linux-x86_64 (native-tls) with rust stable	24s
Linux-x86_64 (native-tls-vendored) with rust stable	1m 40s
Linux-aarch64 with rust stable	40s
Linux-arm with rust stable	56s
Linux-i686 with rust stable	40s
Linux-powerpc with rust stable	48s
Linux-powerpc64 with rust stable	55s
Linux-powerpc64le with rust stable	52s
Linux-riscv64 with rust stable	48s
Linux-s390x with rust stable	31s
NetBSD-x86_64 with rust stable	1m 55s
Windows-aarch64 with rust stable	2m 25s
Windows-i686 with rust stable	1m 47s
Windows-x86_64 with rust stable	2m 38s
macOS-x86_64 with rust stable	29s
macOS-aarch64 with rust stable	28s
Linux-x86_64 with rust beta	37s
Linux-x86_64 with rust nightly	37s
	22m 33s

Provide feedback