Ensure that Nessie-views will not conflict with Iceberg-Views

[snazy]

The draft state of views in Iceberg has been added in #3183, based on initial Iceberg draft for views.
As of today, Iceberg views are not part of any Iceberg release and likely won't make it to Iceberg 0.14.x.

The Iceberg PRs for views are all still WIP and the relevant metadata objects are already different from those in the initial Iceberg draft for views.

We will need a way to ensure that view inforamtion stored in Nessie will never conflict with the final view specification in Iceberg.

Some ideas:

• Update the format-version for views in Nessie: we could change the format-version in Nessie to e.g. 0 and automatically migrate the persisted "draft-state" to "Iceberg view format v1" when fetching an IcebergView. This might be possible, especially after Iceberg metadata in Nessie #3907 - but there's no guarantee, because all Iceberg PRs are still WIP.
• Rip out views from the Nessie code base.
• Do nothing - would break views persisted with the views model in/with Nessie.

Links:

• Iceberg WIP PR: Iceberg View Support
• Iceberg WIP PR: View interfaces
• Iceberg WIP PR: Nessie view support