Make deploykey key parameter sensitive

[tomasmota]

By making it sensitive, it can be loaded from a secretref, instead of a direct secret.

The public key itself might not be a secret, but key pairs are often stored as secrets, so this is a very helpful way to load it. This is also done in the aws provider for example

[tomasmota]

This is a breaking change, so if you accept it make sure to note that in the release ;)

[AtzeDeVries]

Hi @tomasmota,

Thanks, i need to have a think about it. I certainly see the use case for this. The link to the aws provider convinced me :)