Migrate all the non react components code to typescript (#847)

This completes the migration to typescript of all the non react
components code.
The only changes introduced besides types are the type checks using
`"something" in object` which narrows down types in typescript.

src/libs/layer.ts

@@ -0,0 +1,72 @@
+import {latest} from '@maplibre/maplibre-gl-style-spec'
+import { LayerSpecification } from 'maplibre-gl'
+
+export function changeType(layer: LayerSpecification, newType: string) {
+  const changedPaintProps: LayerSpecification["paint"] = { ...layer.paint }
+  Object.keys(changedPaintProps).forEach(propertyName => {
+    if(!(propertyName in latest['paint_' + newType])) {
+      delete changedPaintProps[propertyName as keyof LayerSpecification["paint"]]
+    }
+  })
+
+  const changedLayoutProps: LayerSpecification["layout"] = { ...layer.layout }
+  Object.keys(changedLayoutProps).forEach(propertyName => {
+    if(!(propertyName in latest['layout_' + newType])) {
+      delete changedLayoutProps[propertyName as keyof LayerSpecification["layout"]]
+    }
+  })
+
+  return {
+    ...layer,
+    paint: changedPaintProps,
+    layout: changedLayoutProps,
+    type: newType,
+  }
+}
+
+/** A {@property} in either the paint our layout {@group} has changed
+ * to a {@newValue}.
+ */
+export function changeProperty(layer: LayerSpecification, group: keyof LayerSpecification, property: string, newValue: any) {
+  // Remove the property if undefined
+  if(newValue === undefined) {
+    if(group) {
+      const newLayer: any = {
+        ...layer,
+        // Change object so the diff works in ./src/components/map/MaplibreGlMap.jsx
+        [group]: {
+          ...layer[group] as any
+        }
+      };
+      delete newLayer[group][property];
+
+      // Remove the group if it is now empty
+      if(Object.keys(newLayer[group]).length < 1) {
+        delete newLayer[group];
+      }
+      return newLayer;
+    } else {
+      const newLayer: any = {
+        ...layer
+      };
+      delete newLayer[property];
+      return newLayer;
+    }
+  }
+  else {
+    if(group) {
+      return {
+        ...layer,
+        [group]: {
+          ...layer[group] as any,
+          [property]: newValue
+        }
+      }
+    } else {
+      return {
+        ...layer,
+        [property]: newValue
+      }
+    }
+  }
+}