Following the python guidelines of usage, the operator's Dockerfile has been updated, to use a requirements.txt outside the dockerfile.

Identation fixes

This commit introduces a new bash script, build_and_push_images.sh, which automates the process of building and pushing Docker images for l2sm-switch, l2sm-controller, and l2sm-operator.

This script simplifies the image creation and push workflow, providing options for building images, pushing images, or both.