[dice][refactor] Arrange sample_inputs library and tests in one place

This cl arranges the source code of sample_inputs and its integration
test diced_open_dice_cbor_test in one place.

Bug: 268322533
Test: m microdroid_manager
Test: atest libdiced_sample_inputs.integration_test
Change-Id: I33831b20d719ab43d96b3affb8f478db42ca2739
7 files changed