PB-1383: initial values not included in external layers

Issue: When loading an external WMS layer, the initial values (like the visibility or opacity) were not passed to the layer, which meant that on startup, we would automatically lose their initial state.

Fix: We add the initial values as parameters to the `makeExternalWMSLayer` function.

Author: ltkum

packages/layers/src/parsers/WMSCapabilitiesParser.ts

@@ -538,6 +538,7 @@ function getExternalLayer(
     return layerUtils.makeExternalWMSLayer({
         ...getLayerAttributes(capabilities, layer, parents ?? [], outputProjection, ignoreErrors),
         format: 'png',
+        ...initialValues,
         isLoading: false,
         getFeatureInfoCapability: getFeatureInfoCapability(capabilities, ignoreErrors),
         currentYear,