add base rollup config

src/Umbraco.Web.UI.Client/utils/rollup.config.js

@@ -0,0 +1,14 @@
+import esbuild from 'rollup-plugin-esbuild';
+//import { nodeResolve } from '@rollup/plugin-node-resolve';
+
+/** @type {import('rollup').RollupOptions} */
+export default {
+	input: 'index.ts',
+	external: [/^@umbraco-cms\//, /^@umbraco-ui\//, /^lit/, /^rxjs/],
+	output: {
+		file: 'dist/index.js',
+		format: 'es',
+		sourcemap: true,
+	},
+	plugins: [esbuild({ sourceMap: true })],
+};