This disambiguates "Image" term from "container image" alternative usage
and allows for:
```python
if image_type == LlamaStackImagetype.venv:
...
```
accesses rather than `ImageType.venv.value`
# What does this PR do?
[Provide a short summary of what this PR does and why. Link to relevant
issues if applicable.]
Changes enum use to comply with semantic python styling and naming
conventions.
## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]
Refactor was automated and small so simple run-through of creating
images was done.
Signed-off-by: James Kunstle <jkunstle@redhat.com>