feat: ui overhaul (#676)

packages/core/test/data/config.mock.ts

@@ -0,0 +1,11 @@
+/* eslint-disable import/prefer-default-export */
+import type { BaseField, Config } from '@staticcms/core';
+
+export const createMockConfig = <EF extends BaseField>(
+  options: Omit<Partial<Config<EF>>, 'collections'> & Pick<Config<EF>, 'collections'>,
+): Config<EF> => ({
+  backend: {
+    name: 'test-repo',
+  },
+  ...options,
+});