Add project: don't show VCS SSO organization if the user is not the owner

[humitos]

I selected an organization with VCS SSO that it seems I'm member of

but then I got this error

I suppose we should not show VCS SSO organization in the first selector if we are not the owner. cc @agjohnson thoughts? Do we need to communicate to users that there may be organization that don't appear in the selector because of this reason?

[agjohnson]

I might say the same as #467 here and we should show an error/disabled state. I think for now this UX is okay-ish, and agree it would be more confusing for the organization to be missing from the list.