Replace Ledger `connect-kit` loader with a direct dependency

Concerning the recent Ledger exploit, the dashboard should no longer use `@ledgerhq/connect-kit-loader` to dynamically load `@ledgerhq/connect-kit` from CDN. As per https://github.com/LedgerHQ/connect-kit/pull/30#issuecomment-1857639914, the loader library is now deprecated and should be replaced with a direct dependency to `@ledgerhq/connect-kit` in version `>= 1.1.8`.