[flang] Map symbols in expressions when copying interface symbols

Given a MODULE SUBROUTINE or MODULE FUNCTION interface followed
later by a corresponding separate module subprogram definition in a
MODULE PROCEDURE, the copies of the interface's dummy argument and
function result symbols that populate the initial scope of that
MODULE PROCEDURE need to have any symbol references in their types
or bounds adjusted to point to their new counterparts.

Differential Revision: https://reviews.llvm.org/D139200