Provides a mechanism to avoid mirroring unnecessary architecture's images

1. Proposed title of this feature request

• Provides a mechanism to avoid mirroring unnecessary architecture's images

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

• If the customer has only x86 Intel and AMD servers in their cluster, when configuring OperatorHub for restricted networks, they would like to mirror their necessary linux/amd64 images only.
• In this case, they need the following steps:

1) Extract the contents of custom Operator catalog image to image to generate the manifests
   required for mirroring with "--filter-by-os="linux/amd64" and "--manifests-only" option.
    $ oc adm catalog mirror ... --filter-by-os="linux/amd64" --manifests-only
2) Modify the list of images in mapping.txt file to custome's specifications.
3) Mirror the images to customer's registry using the "oc image mirror" as follows:
    $ oc image mirror ... --filter-by-os=".*" -f ./redhat-operators-manifests/mapping.txt

• If they run "oc iamge mirraor" without --filter-by-os=".*" option, then they will fail to deploy the images.
• So, in this case, they need to mirror all of the architecture's images, it means that mirroring time and disk space for unnecessary Operator catalog images file would be wasted.
• The customer wants to eliminate these wastes.
• Refer to comment#20 in RHBZ#1851543[1]
  [1] https://bugzilla.redhat.com/show_bug.cgi?id=1851543#c20

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

• The customer wants to eliminate the mirroring time and disk space for unnecessary Operator catalog images.

4. List any affected packages or components.

• Uncertain