Moved maps and tokens to a data source model

This will allow for easier custom token support as well as changing default tokens

src/helpers/useDataSource.js

@@ -0,0 +1,29 @@
+import { useEffect, useState } from "react";
+
+// Helper function to load either file or default data
+// into a URL and ensure that it is revoked if needed
+function useDataSource(data, defaultSources) {
+  const [dataSource, setDataSource] = useState(null);
+  useEffect(() => {
+    if (!data) {
+      return;
+    }
+    let url = null;
+    if (data.type === "file") {
+      url = URL.createObjectURL(data.file);
+    } else if (data.type === "default") {
+      url = defaultSources[data.name];
+    }
+    setDataSource(url);
+
+    return () => {
+      if (data.type === "file" && url) {
+        URL.revokeObjectURL(url);
+      }
+    };
+  }, [data, defaultSources]);
+
+  return dataSource;
+}
+
+export default useDataSource;