Finish the implementation of IdentifyValuesUsedInOtherOffloads

[strongoier]

The implementation of IdentifyValuesUsedInOtherOffloads is not finished yet:

taichi/taichi/transforms/offload.cpp

Lines 269 to 272 in 153f338

	// Traverse offloaded blocks to identify out-of-offload local LD/ST and
	// statement references
	class IdentifyValuesUsedInOtherOffloads : public BasicStmtVisitor {
	using BasicStmtVisitor::visit;

More specifically, most statements currently go through:

taichi/taichi/transforms/offload.cpp

Lines 345 to 351 in 153f338

	void visit(Stmt *stmt) override {
	int n_op = stmt->num_operands();
	for (int i = 0; i < n_op; i++) {
	auto op = stmt->operand(i);
	test_and_allocate(op);
	}
	}

However, the operands involved in many of them are not present at the operands member variable, therefore they will not be handled. #3463 is an example of a result bug and #3466 is an example of the corresponding fix.

To avoid future appearance of such bugs, we need to finish the implementation of this class.