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

[lukasz-zimnoch]

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 LedgerHQ/connect-kit#30 (comment), the loader library is now deprecated and should be replaced with a direct dependency to @ledgerhq/connect-kit in version >= 1.1.8.