Add shell scripts to verify DTO

Add two shell scripts to verify DTO (device tree overlay).

verify_dto_inc.sh uses syntax /include/ to simulate DTO.

verify_dto_ovl.sh uses dtc to compile dts to dtb,
and uses ufdt_overlay_test_app which implemented with libufdt to
apply DTO.

Also modified test code and test cases to use these shell scripts.

Bug: 33954716
Test: run test scripts (see libufdt/tests/README)
Change-Id: Iaa16d6d2b9a6cb767ed0cf25180b0e6ee290415d