[query] Delete Bindings, AggEnv and GenericBindingEnv

Nothing calls the old scoping code now that every caller uses ChildEnv.get.
This deletes Bindings, AggEnv, GenericBindingEnv and BindingEnv's extend,
subtract and bindRelational, plus BindingEnv and Env helpers that were
already unused on main, and the IndexedSeq[Int] binding helpers on the
TableType and MatrixType companions. It also deletes IRSuite's test that
checked ChildEnv against Bindings.get. The IR checklist now names ChildEnv
and Binds.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: ehigham