[dice] Move dice bindgens next to their safe wrapper library

This cl moves the open-dice cbor and bcc bindgens and their tests
next to their safe wrapper library so that we can limit their
visibility only to :__subpackges__ to align with the rust bindgen
recommendation[1].

[1] https://source.android.com/docs/setup/build/rust/building-rust-modules/source-code-generators/bindgen-modules#visibility-and-linkage
Bug: 267575445
Test: m pvmfw_img microdroid_manager

Change-Id: I04e6861600c8d40120041e7eaec7fb468a4dc00a
4 files changed