Show all imagestreams in imagestream file

[phracek]

This pull request shows all tags in all imagestream json files.

It replaces this pull request https://github.com/sclorg/container-common-scripts/pull/256

[phracek]

In real usecase, I tested it on postgresql-container.

python3 /root/postgresql-container/test/show_all_imagestreams.py
Tags in the image stream imagestreams/postgresql-centos.json:
- 10-el8 -> quay.io/sclorg/postgresql-10-c8s:latest
- 12-el8 -> quay.io/sclorg/postgresql-12-c8s:latest
- 13-el8 -> quay.io/sclorg/postgresql-13-c8s:latest
- 15-el8 -> quay.io/sclorg/postgresql-15-c8s:latest
- 13-el9 -> quay.io/sclorg/postgresql-13-c9s:latest
- 15-el9 -> quay.io/sclorg/postgresql-15-c9s:latest
- 16-el9 -> quay.io/sclorg/postgresql-16-c9s:latest
- latest -> 16-el9
Tags in the image stream imagestreams/postgresql-rhel-aarch64.json:
- 10-el8 -> registry.redhat.io/rhel8/postgresql-10:latest
- 12-el8 -> registry.redhat.io/rhel8/postgresql-12:latest
- 13-el8 -> registry.redhat.io/rhel8/postgresql-13:latest
- 15-el8 -> registry.redhat.io/rhel8/postgresql-15:latest
- 13-el9 -> registry.redhat.io/rhel9/postgresql-13:latest
- 15-el9 -> registry.redhat.io/rhel9/postgresql-15:latest
- 16-el9 -> registry.redhat.io/rhel9/postgresql-16:latest
- latest -> 16-el9
Tags in the image stream imagestreams/postgresql-rhel.json:
- 10-el7 -> registry.redhat.io/rhscl/postgresql-10-rhel7:latest
- 12-el7 -> registry.redhat.io/rhscl/postgresql-12-rhel7:latest
- 13-el7 -> registry.redhat.io/rhscl/postgresql-13-rhel7:latest
- 10-el8 -> registry.redhat.io/rhel8/postgresql-10:latest
- 12-el8 -> registry.redhat.io/rhel8/postgresql-12:latest
- 13-el8 -> registry.redhat.io/rhel8/postgresql-13:latest
- 15-el8 -> registry.redhat.io/rhel8/postgresql-15:latest
- 13-el9 -> registry.redhat.io/rhel9/postgresql-13:latest
- 15-el9 -> registry.redhat.io/rhel9/postgresql-15:latest
- 16-el9 -> registry.redhat.io/rhel9/postgresql-16:latest
- latest -> 16-el9

[phracek]

[test]

[zmiklank]

@phracek In that case we can also remove "import sys".