Add iceberg.rest-catalog.prefix as a catalog session property

[goober]

Proposal

Enable the iceberg.rest-catalog.prefix to be set as a catalog session property.

Rationale

The Nessie catalog uses the iceberg.rest-catalog.prefix property to point to the catalog branch to use. See Nessie documentation. If it was possible to set this property on a session it would enable a Trino user to independently write and read data on any given branch that is available in the Nessie catalog. Even though the branch creation is handled outside of Trino

If the proposal is accepted I would be happy to contribute.

[ebyhr]

@goober Allowing branch changes with session property may lead to mistake because users have to remember the current session values.

We started the discussion about the branching syntax recently. We will share the document once it's ready for publish.