Add skeleton for future feature support

- Future feature is for feature which will not be enabled by default.
- These features are not ready yet and should not be used for
  production.
- APIs marked with FutureFeature annotation is for APIs under development.
  Those APIs should never used for production.

bug: 34710797
Test: build

Change-Id: If5d001f31b770fc6ba7bce084d98ce3c1fc1850f
5 files changed