✨clusterctl: add version command

[fabriziopandini]

What this PR does / why we need it:
This PR imports a cleaned version of the /version package from CAPA and then implements the clusterctl version command

rif #1729

[chuckha]

Would you be able to add some documentation around build args on how to use this?

[fabriziopandini]

changing the scope of the PR as discussed in slack

[fabriziopandini]

Nb. I'm ignoring few shell-check errors in the version.sh file to get the validation pass (the script is copy/paste from CAPA)

[randomvariable]

Nb. I'm ignoring few shell-check errors in the version.sh file to get the validation pass (the script is copy/paste from CAPA)

That's fair, given the CAPA script is itself taken from k/k

[randomvariable]

/lgtm

[vincepri]

/approve

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[fabriziopandini]

Would you be able to add some documentation around build args on how to use this?

@chuckha ATM I'm not planning to add documentation given that this mirrors what exists in CAPA and that variables are automatically set when building clusterctl