allow oc-mirror list operators to re-use catalog images

1. Proposed title of this feature request

oc-mirror should be able to be used to check for new releases of operators

2. What is the nature and description of the request?

Current the `oc-mirror list operators` command runs as a single instance which takes significant time as it downloads the catalog image everytime the image runs.

The proposed augmentation is to enable reusability of downloaded catalog images. This will drastically improve the time required to run queries against operator versions and channels.

3. Why does the customer need this? (List the business requirements here)

• Managing operator versions is time consuming as each `oc-mirror list operators` command takes approximately 3 minutes to run. It is common to require at least 2-3 runs of `oc-mirror list operators` for each operator added to the `ImageSetConfiguration`

• There currently isn't an effective method to parse the operator catalog for operator updates in a disconnected environment which makes managing operator versions time consuming and vary manual

4. List any affected packages or components.
oc-mirror