Raster GetFeatureInfo response does not show FeatureInfo

[jacobwod]

Describe the bug
WMS can be configured to respond with a value that is calculated by the service and mapped accordingly to some specification. One common use case are heat maps, where each color corresponds to a numeric value.

When we configure such a layer and try to display it's value in infoclick, the result will be an empty FeatureInfo window.

The reason for this is that Hajk can't find out which infoclickDefinition should be used because the WMS response lacks feature ID. (It actually lacks the feature entirely.)

We still have a value though and we want to show it in FeatureInfo.

Proposed solution
Currently this method tries to find out the layer name:

Hajk/new-client/src/models/MapClickModel.js

Line 62 in ae8a971

#getLayerNameFromFeatureAndLayer = (feature, layer) => {

. This name is then used to grab the correct infoclick definition.

One way to solve it is to distingiush features where geometry is null and getId() returns undefined. This would indicate our special scenario. In this case we can try to just grab the first infoclick definition in current layer and try to use it.

Not a perfect solution but it could work.

Another solution
We might also implement some special case as described in this article: https://docs.geoserver.org/stable/en/user/tutorials/GetFeatureInfo/raster.html