enhance linting for installModes

[brianwcook]

courier did not throw a linting error for following config:

installModes:

• type: OwnNamespace
  supported: true
• type: SingleNamespace
  supported: false
• type: MultiNamespace
  supported: false
• type: AllNamespaces
  supported: false

but SingleNamespace or (inclusive) AllNamespaces should be true, as well as OwnNamespace
supported: true

[awgreene]

To add to @brianwcook comment. @SamiSousa has confirmed that OwnNamespace should always be true so we should check for that.

Although there is no way for us to know if an operator should be able to watch SingleNamespaces, MultiNamespaces, or AllNamespaces, we should confirm that at least one of these are set to true.