Use Sensitive data type for passwords

Currently, the master password of the whole infrastructure is displayed in the logs when the install exec fail:

Error: '/usr/sbin/ipa-client-install [...] --password='myverysecurepassword' [...]

Obviously, it is not a very secure way to display sensitive informations. This patch store the password into an environment variable, at least the password is not displayed in the logs when the exec fail:

Error: '/usr/sbin/ipa-client-install [...] --password="$PASSWORD_USEDTO_JOINDOMAIN" [...]

I’ve also added support to provide the password as Sensitive type, which exists in puppet 6 and puppet 7. Not supported on Puppet 5 (which is claimed to be supported in metadata.json) but is EOL. I’ve adjusted the metadata.json. Also added tests about this feature.

Any feedback is welcome!