Revert "Delete unused classes"

This reverts commit 2fa45c92e6c887b351174afbf715589bcca57423.
It bring back SlidingTabLayout.java which will be used for
multi-SIM configurations.

Bug: 65648147
Test: unittest
Change-Id: I84c75a2e1d33fc89f58165c662d82a8ad3d6ef20
5 files changed