Adds a CLI to oslo_utils.imageutils which can be used to validate
images.
Example usages:
$ python -m oslo_utils.imageutils -i ./gpt-image.raw -v
SAFETY_CHECK_PASSED=True
VIRTUAL_SIZE=262144
ACTUAL_SIZE=262144
IMAGE_FORMAT='gpt'
OSLO_UTILS_VERSION='7.4.0.dev1'
$ python -m oslo_utils.imageutils -i ./bad-qed.qed -v
SAFETY_CHECK_PASSED=False
VIRTUAL_SIZE=262144
ACTUAL_SIZE=262144
IMAGE_FORMAT='qed'
OSLO_UTILS_VERSION='7.4.0.dev2'
FAILURE_REASONS='banned: This file format is not allowed'
Change-Id: Ia94fa0431a55ab599ffd7385f2be1b18cf4bb1c4
8e6cf95564