[vsphere] Test the use of a global propergate read-only role

As a openshift engineer determine if the vSphere permission set should include the built in ReadOnly role at the top-level of vCenter so all objects in the tree can be read.

• • Notes **
    While assisting with this thread:
    https://coreos.slack.com/archives/CH06KMDRV/p1654185920344629

Determined that our CI vCenter logs were repeating the same messages as a customer's environment.

• • Acceptance Criteria **

• Create a ReadOnly group and add the role at the top-level of vCenter
• Add a test user to the readonly group
• Confirm the test user does not have errors
• Documentation update