Security Contexts not allowed in mattermost-operator deployment.

[frjaraur]

Secure Kubernetes cluster require security contexts definitions to allow definition of user/group execution, seLinux contexts or specific pod capabilities, among many other features.
I added security context option (and example values in values file) y mattermost-operator chart.
It was tested and it is working on staging cluster, waiting for new changes as mattermost instances does not inherit these definitions in their deployments.
Hope it helps,
JR