gccrs: Add checks to ExpandVisitor

gccrs: Add checks to ExpandVisitor

This should help detect issues like
https://github.com/Rust-GCC/gccrs/issues/3444.

gcc/rust/ChangeLog:

	* ast/rust-ast.h (Stmt::get_node_id): Make virtual.
	(Type::get_node_id): Likewise.
	(AssociatedItem::get_node_id): New virtual member function.
	* ast/rust-expr.h (TypeCastExpr::get_casted_expr_ptr): New
	member function.
	(TypeCastExpr::get_type_to_cast_to_ptr): Likewise.
	(ClosureExprInner::get_definition_expr_ptr): Likewise.
	* ast/rust-item.h (TypeAlias::get_node_id): New member function
	to override AssociatedItem::get_node_id.
	(ConstantItem::get_node_id): Likewise.
	* expand/rust-expand-visitor.cc
	(ExpandVisitor::maybe_expand_expr): Adjust
	macro_invoc_expect_id.
	(ExpandVisitor::maybe_expand_type): Likewise and add an overload
	for std::unique_ptr<TypeNoBounds>.
	(ExpandVisitor::visit): Check macro_invoc_expect_id and
	generally improve visitors so that the testsuite will still
	pass.
	* expand/rust-expand-visitor.h (ExpandVisitor::ExpandVisitor):
	Initialize member variable macro_invoc_expect_id.
	(ExpandVisitor::maybe_expand_type): Add an overload for
	std::unique_ptr<TypeNoBounds>.
	(ExpandVisitor::expand_macro_children): Adjust
	macro_invoc_expect_id.
	(ExpandVisitor::visit): Add an overload for TypeCastExpr.
	(ExpandVisitor::macro_invoc_expect_id): New member variable.

gcc/testsuite/ChangeLog:

	* rust/compile/macros/mbe/macro49.rs: Add missing lang items.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>