Feat: Update to Podman, Ubuntu 24.04, CS Stream 9

Feat: Update to Podman, Ubuntu 24.04, CS Stream 9

- Switch from Docker to Podman driver for Molecule tests
- Add Ubuntu 24.04 and CentOS Stream 9 platform support
- Remove EOL platforms (Ubuntu 18.04, 20.04, CentOS 7/8)
- Update GitHub Actions workflow:
  - Install Podman on runners
  - Use requirements.txt for Python dependencies
  - Set MOLECULE_PROJECT_DIRECTORY and ANSIBLE_ROLES_PATH
- Add gather_facts: true to converge.yml
- Add requirements.txt with molecule-plugins[podman]

Change-Id: Ie7124ce0b0190ce0a51a7d5cd6d2debcdb5fc596
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>