Refactor fullmte bits into common dir Pull fullmte-common and fullmte-vars into a common dir so they can also be used by other devices. See the topic changes for device/google/gs-common. Bug: 288843255 Test: run soong for shiba_fullmte, build/flash husky_fullmte. Change-Id: I6cc636596acff8b5234197fe26f85e27f7e85a62