feat(v2): Make ResourceNames::ensure_max_length public

[sbernauer]

Description

I need this helper function to fix a bug in commons-operator: stackabletech/commons-operator#443

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[siegfriedweber]

This constant belongs in kvp::annotation.

Rather than exposing the value publicly, it might be cleaner to offer a sanitize function that takes a key prefix and name and returns a valid kvp::key::Key.

[siegfriedweber]

This function was written for resource names, where the assertions always hold. If it's now used to shorten arbitrary strings (which could also come from the user) then you can expect the operator to crash.

That said, I do see the usefulness. I'd suggest making it safe for arbitrary strings (which isn't trivial) and moving it to a string utility module.