[murmur] add new chart

[GenericEric]

Description of the change

Adds Murmur chart (Mumble Voice Chat)

Benefits

Easy way to deploy Murmur on Kubernetes. I think this is the first helm chart for it.

Checklist

• [X ] Title of the PR starts with chart name (e.g. [home-assistant])
• [ X] Chart version bumped in Chart.yaml according to semver.
• [ X] Chart artifacthub.io/changes changelog annotation has been updated in Chart.yaml. See Artifact Hub documentation for more info.
• [X ] Variables have been documented in the values.yaml file.