[REFACTOR] Twenty UI multi barrel (#11301)

# Introduction
closes https://github.com/twentyhq/core-team-issues/issues/591
Same than for `twenty-shared` made in
https://github.com/twentyhq/twenty/pull/11083.

## TODO
- [x] Manual migrate twenty-website twenty-ui imports

## What's next:
- Generate barrel and migration script factorization within own package
+ tests
- Refactoring using preconstruct ? TimeBox
- Lint circular dependencies
- Lint import from barrel and forbid them

### Preconstruct
We need custom rollup plugins addition, but preconstruct does not expose
its rollup configuration. It might be possible to handle this using the
babel overrides. But was a big tunnel.
We could give it a try afterwards ! ( allowing cjs interop and stuff
like that )
Stuck to vite lib app

Closed related PRs:
- https://github.com/twentyhq/twenty/pull/11294
- https://github.com/twentyhq/twenty/pull/11203

packages/twenty-ui/src/utilities/config.ts

@@ -0,0 +1,28 @@
+declare global {
+  interface Window {
+    _env_?: Record<string, string>;
+    __APOLLO_CLIENT__?: any;
+  }
+}
+
+const getDefaultUrl = () => {
+  if (
+    window.location.hostname === 'localhost' ||
+    window.location.hostname === '127.0.0.1'
+  ) {
+    // In development environment front and backend usually run on separate ports
+    // we set the default value to localhost:3000.
+    // In dev context, we use env vars to overwrite it
+    return 'http://localhost:3000';
+  } else {
+    // Outside of localhost we assume that they run on the same port
+    // because the backend will serve the frontend
+    // In prod context, we use index.html + window var to ovewrite it
+    return `${window.location.protocol}//${window.location.hostname}${
+      window.location.port ? `:${window.location.port}` : ''
+    }`;
+  }
+};
+
+export const REACT_APP_SERVER_BASE_URL =
+  window._env_?.REACT_APP_SERVER_BASE_URL || getDefaultUrl();