WIP: support multiple images

[unfor19]

Closes #132

Tested and it works as expected, also ran the ./run_tests.sh.

Example of usage below

--image-map       Find and replace image names per container according to a map. Overrides --image
                  Format: [image_str_contains1],[image1];[image_str_contains2],[image2]
                  Examples: ubuntu:18.04,ubuntu:20.04;nginx:1.18.0,nginx:1.19.9-alpine
                  Replaces all images that contain "ubuntu:18.04" with "ubuntu:20.04" and all images that contain "nginx:1.18.0" with "nginx:1.19.0-alpine"

This is a Work In Progress (WIP) since I've also added the --dry-run to be able to test it locally. Still haven't decided if I want to keep it in this PR

[jfranzoi]

hello @unfor19 I think we were working on related stuff recently!

I prepared a PR for having the --image being applied on the main container image's only (where main means the first one). see #227

I think those can nicely live side by side anyway 👍
@fillup any feedback on this?

[devon-sil]

Given the age of this PR and that it has conflicts, I'm going to close it out. If you still want to pursue this, please submit a new PR based on the latest code.