Strip subnet mask from HetznerBareMetalHost IP Address

[Strangerxxx]

What this PR does / why we need it:
It basically strips subnet mask suffix from the NIC IP for BaremetalHost, so it became correctly recognized as IP by other providers of ClusterAPI ecosystem.

Previously IP was a string like: 37.27.255.255/16

After this changes IP will become a string 37.27.255.255

TODOs:

• squash commits
• include documentation
• add unit tests

[guettli]

@Strangerxxx looks good. But please elaborate the PR description first. Please provide an example of the current and the new IP

[Strangerxxx]

@guettli thank you for review!

I've add examples you've asked for.

Please let me know what else should be done.

I'm happy to fix it asap :)

[guettli]

@Strangerxxx I know that the term "IP" does not match the content (37.27.255.255/16), because it is a "subnet".

If you are looking for the IP, then you can use spec.status.ipv4.

You propose a change to spec.status.hardwareDetails.nics[].ip. This field is not defined in cluster api. The reason "capi ecosystem" ... please elaborate what you mean.

Currently, I am slightly against this change, because I have concerns that removing /16 could break existing tooling build upon caph.

Please elaborate your current pain point, and how this PR would help.