core: Update Hillshade Algorithms and add Color-Relief Layer support (#3965)

metrics/integration/render-tests/hillshade-low-zoom/igor/style.json

@@ -0,0 +1,39 @@
+{
+  "version": 8,
+  "metadata": {
+    "test": {
+      "height": 256,
+      "width": 256,
+      "description": "This test verifies hillshade rendering with igor method at low zoom levels (zoom 1) where exaggeration scaling is applied"
+    }
+  },
+  "center": [0, 45],
+  "zoom": 1,
+  "sources": {
+    "source": {
+      "type": "raster-dem",
+      "tiles": [
+        "local://tiles/{z}-{x}-{y}.terrain.png"
+      ],
+      "maxzoom": 15,
+      "tileSize": 512
+    }
+  },
+  "layers": [
+    {
+      "id": "background",
+      "type": "background",
+      "paint": {
+        "background-color": "white"
+      }
+    },
+    {
+      "id": "hillshade",
+      "type": "hillshade",
+      "source": "source",
+      "paint": {
+        "hillshade-method": "igor"
+      }
+    }
+  ]
+}