Print version and commit hash on startup

[schrej]

In order to identify the exact version running on a cluster, in case a hand-crafted image is used for example, the operator should output it's version and it's commit hash on startup.

Version and hash should be set when building the binary using go ldflags, which allows changing vars at build time. CAPI has a good approach for making those values read-only:
https://github.com/kubernetes-sigs/cluster-api/blob/main/version/version.go