use less-than instead of not-equal when comparing key sizes

[szubersk]

When evaluating policy compliance, use less-than operator so keys bigger than expected (and hence very often better) don't fail policy evaulation. This change reduces the amount of false-positives and allows for more flexibility when hardening SSH installations.

[pepoluan]

Can we merge this? Please?

[pepoluan]

Alternatively ...

Make the comparison a function that looks kinda like this:

def key_size_complies(expected: int, actual: int):
    if global_flag_keysize_must_match:
        return expected == actual
    return expected <= actual

So just in case there are companies that requires exact key size (rather than minimum key size), we can set global_flag_keysize_must_match to True (perhaps via an option like --keysize-exact)

Or alternatively turn the logic around so people relying on prior behavior doesn't get an unexpected suprise, so make the option --keysize-as-minimum.

[szubersk]

@jtesta what do you think about this PR?

[jtesta]

@pepoluan , @szubersk : I'll be reviewing this PR soon. I'm planning for a release by the end of this month, and either this PR or something similar will likely be included.

[jtesta]

@szubersk : thanks for submitting this PR!