Function getMaplibreSourceIdByJMapLayerId

getMaplibreSourceIdByJMapLayerId(layerId): string
JMap.Map.getMaplibreSourceIdByJMapLayerId

Returns the source id of the given Jmap layer id.
Parameters
- layerId: JId
  the JMap layer id
Returns string
Throws
if invalid JMap layer id or if JMap layer doesn't exist

Example
```
// returns the source id of the JMap layer with id 4
JMap.Map.getMaplibreSourceIdByJMapLayerId(4)
```