Add `cacert` option to `.litmusconfig`

[alininja]

Hi Awesome LitmusCTL Team 👋

This ticket is the result of this Slack discussion: https://kubernetes.slack.com/archives/CNXNB0ZTN/p1714515065327229

Please add an option to specify the cacert within the .litmusconfig file.

This can be helpful for CI/CD pipelines running against internal Chaos Centers that uses self-signed certficates.

Thank you for your consideration 🙏