Fail on missing privileges for VSphere user

[vivek-koppuru]

Currently, we throw a warning if there are missing privileges for a VSphere user in the form of a -v=3 log. We started off with a hard fail #2907 but moved to a warning #3160 to allow users to continue with the workflow. Now that we have --skip-validations as an option #5697, we should switch back to hard failing but allowing for the checks to be bypassed through this flag so that we better alert users instead of issues happening with creation/upgrade later in the workflow.