[murmur] add new murmur chart

[GenericEric]

Description of the change

Adding a new chart for Murmur (Mumble Voice Chat Server)

Benefits

An easy and robust way to run Murmur on Kubernetes using helm, which I don't think exists yet.

Possible drawbacks

Uses NodePort by default. LoadBalancer may be preferred for some.

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.