More consistent structure in Hibernate Dev UIs

Description

After #46728 the Hibernate ORM dev UI looks like below.

The structure is a bit inconsistent, let's improve on that? In particular:

1. There's a top tab for "persistence units", but then the content of each tab also shows content that is essentially "per persistence unit". That tab should probably be named "DDL" instead?
2. Persistence unit selection is done differently in "DDL"/"Entities"/"Named queries" tabs (one tab per persistence unit) vs. "HQL console" (select box). I would suggest using a single select box, putting it at the very top, to the left of the row of tabs. Note that might require changes to Dev UI support in Quarkus, but @phillip-kruger would be able to point us in the right direction.
3. The same probably holds for the Dev UI of Hibernate Search extensions (ORM + Standalone) too.

Implementation ideas

No response