[flang] Stricter scrutiny of deferred type parameters (C702)

Semantics checks C702, which disallows deferred type parameters for
any entity that is neither an allocatable nor a pointer, only during
name resolution of type declaration statements.  This check needs to
be broader, since Fortran entities can have their types specified in
other ways.  Rewrite the check and move it to the general declaration
checking pass.

Differential Revision: https://reviews.llvm.org/D136970