The UploadImage method doesn't actually create an image. It creates a Page
Blob. Blob is something like S3 object but in the Azure terminology. Page
Blob means that's optimized for random access and it's the only blob type
that can be used to create images.
This commit cleans up the terminology so it's less confusing.
Signed-off-by: Ondřej Budai <ondrej@budai.cz>
More specifically only those that are needed in
/cmd/osbuild-image/tests.
This patch can be merged with the previous one if we want to make sure
every commit can be built, but I'm going to keep it like this for now so
that we can easily see the changes.
