Implementing a test suite was impossible outside of the
k8s.io/kubernetes/test/e2e/storage/testsuites package because all
interfaces and structs used by them were private.
As part of revamping the API, genericVolumeTestResource also gets
exported because it is useful for other test suites. Because the
TestResource interface became obsolete a while ago and isn't used
anymore, the new name is just testsuites.VolumeResource.
testpatterns.CSIInlineVolume needs special handling in a few places.
It can now be used in a test pattern for a test suite that uses a
VolumeResource instance.
test/e2e/storage/testsuites creates volumes dynamically. Initially, the size of those volumes was
hard-coded in the test, which prevented using the tests with storage backends that couldn't support
that hard-coded size
