NodeExpandVolume sanity tests are available in CSI sanity testsuite

[Hemant Kumar]

Hello folks,

If you are a CSI driver author or user - I wanted to bring your
attention to two things:

1. NodeExpandVolume has been added to the list of things we validate
while running CSI sanity test now.
2. By default - CSI sanity test will *always* call NodeExpandVolume
*after* NodePublish and it is expected that if your driver supports
Node expansion then NodeExpandVolume after NodePublish should work
too. We are planning to change the wording in the spec to recommend
that CO should call NodeExpandVolume after NodePublish. See the
discussion here -
https://github.com/container-storage-interface/spec/pull/428#issuecomment-631733052

Thank you.