[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-front/src/loading/components/UserOrMetadataLoader.tsx

@@ -1,9 +1,9 @@
 import styled from '@emotion/styled';
-import { MOBILE_VIEWPORT } from 'twenty-ui';
 
 import { NAV_DRAWER_WIDTHS } from '@/ui/navigation/navigation-drawer/constants/NavDrawerWidths';
 import { LeftPanelSkeletonLoader } from '~/loading/components/LeftPanelSkeletonLoader';
 import { RightPanelSkeletonLoader } from '~/loading/components/RightPanelSkeletonLoader';
+import { MOBILE_VIEWPORT } from 'twenty-ui/theme';
 
 const StyledContainer = styled.div`
   background: ${({ theme }) => theme.background.noisy};