Update all plugins to new frontend and backend component systems

[f0ssel]

We are currently on the legacy plugin system and will need to upgrade to continue to work with latest backstage versions.

• https://backstage.io/docs/frontend-system/
• Current Open PR - Migrate the Frontend Coder Plugin to NFS #149

[Parkreiner]

The main question I have around the migration is whether we might need to have two versions of the demo app until the old systems are fully deprecated