bpart: Also partition ->deprecated (#57449)
This repeats the exercise in #57405. This is required for correctness,
because the ->deprecated flag also affects `using` resolution (since it
makes the tagged binding weaker for `using` purposes). That said, in
general our `->deprecated` semantics have been somewhat underspecified
with lots of `XXX` comments in the surrounding code. This tries to
define the semantics to give a depwarn on *access* (read or write) when:
1. Either the binding itself is deprecated; or
2. The implicit imports pass through a deprecated binding.
However, we do not give depwarns on access to bindings that were
explicitly imported (although we do give those warnings on the import) -
the reasoning being that it's the import that needs to be adjusted not
the access.
Additionally, this PR moves into the direction of making the depwarn a
semantic part of the global access, by adjusting codegen and inference
appropriately.
