subresource_api_test: Improve expand spec subresources tests
subresource_api_test: Improve expand spec subresources tests

Improved and added new functional tests for the
expand-spec/expand-vm-spec subresource endpoints. Test now cover
namespaced and cluster-wide instancetypes and preferences.

Co-authored-by: Lee Yarwood <48c413690cc1868fd4674765d19c7979f048b748@redhat.com>
Co-authored-by: Andrej Krejcir <cd319b80dc788d308d262d82d71619ebc6569033@redhat.com>
Signed-off-by: Felix Matouschek <d5fbe2d618e1c455cad8aae93704618a66caf026@redhat.com>

kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt