Reapply "[mlir] Mark `isa/dyn_cast/cast/...` member functions depreca… (#90406)

…ted. (#89998)" (#90250)

This partially reverts commit 7aedd7dc.

This change removes calls to the deprecated member functions. It does
not mark the functions deprecated yet and does not disable the
deprecation warning in TypeSwitch. This seems to cause problems with
MSVC.