Missing values in helm templates

In the helm chart, two values are missing, as previously added in Minecraft bedrock.
https://github.com/itzg/docker-minecraft-bedrock-server/blob/ab51be217cf5f245fcb3239466f145af3a9422ba/property-definitions.json#L112

https://github.com/itzg/docker-minecraft-bedrock-server/blob/ab51be217cf5f245fcb3239466f145af3a9422ba/property-definitions.json#L116

I did not find those two values can be easily controlled in the helm chart values.

```yaml
"emit-server-telemetry": {
"env": "EMIT_SERVER_TELEMETRY",
"allowed": ["true","false"]
},
"enable-lan-visibility": {
"env": "ENABLE_LAN_VISIBILITY",
"allowed": ["true","false"]
}
```

I expect this feature can be added.

Start by inspecting the Helm chart's values and templates, then compare the available settings with the two referenced entries in property-definitions.json. Add chart controls for EMIT_SERVER_TELEMETRY and ENABLE_LAN_VISIBILITY, accepting true or false, and verify that both settings can be configured through the chart values.

Written by the indexing model from the issue text.