cli: add esm loader for exterminal backend start

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Co-authored-by: Camila Belo <camilaibs@gmail.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/cli/package.json

@@ -41,6 +41,7 @@
     "@backstage/release-manifests": "workspace:^",
     "@backstage/types": "workspace:^",
     "@esbuild-kit/cjs-loader": "^2.4.1",
+    "@esbuild-kit/esm-loader": "^2.5.5",
     "@manypkg/get-packages": "^1.1.3",
     "@octokit/graphql": "^5.0.0",
     "@octokit/graphql-schema": "^13.7.0",

packages/cli/src/lib/experimental/startBackendExperimental.ts

@@ -25,7 +25,12 @@ import debounce from 'lodash/debounce';
 import spawn from 'cross-spawn';
 import { paths } from '../paths';
 
-const loaderArgs = ['--require', require.resolve('@esbuild-kit/cjs-loader')];
+const loaderArgs = [
+  '--require',
+  require.resolve('@esbuild-kit/cjs-loader'),
+  '--loader',
+  require.resolve('@esbuild-kit/esm-loader'),
+];
 
 export async function startBackendExperimental(options: BackendServeOptions) {
   const envEnv = process.env as { NODE_ENV: string };