Add MLflow kserve-example

[misohu]

Add MLflow example with K-serve deployment. To properly test it you need to deploy mlflow with kubeflow according to these instructions. After that you need to add three extra relations (for k-serve integration).

juju relate kserve-controller:service-accounts resource-dispatcher:service-accounts
juju relate kserve-controller:secrets resource-dispatcher:secrets
juju relate kserve-controller mlflow-minio

[misohu]

Thanks @orfeas-k I completely change the example according to our UAT https://github.com/canonical/charmed-kubeflow-uats/pull/42

[misohu]

Fixed thanks @orfeas-k