Allow exact version match

[jonhutchens]

In some scenarios, in may be desirable to have a config option to force an exact version match instead of using +-1 minor revision of the k8s cluster. For example, I'm seeing this issue where EKS seemingly has failed to properly support the +-1 minor version rule and thus kubectl 1.24 does not work with a 1.23 EKS cluster. So if there was an option for kuberlr to allow the user to specify an exact version match, we could workaround issues like this more easily. I'm guessing the use case could be even broader than this though.

[jandubois]

I can see multiple potential policies that you may want:

• allow current ±1 version skew
• use exact match
• use exact match or +1, in case you want to make use of a new beta feature that is not supported by the -1 client

But maybe it is good enough to use the exact version match policy for the last case as well, to keep things simple.