Added skeleton classes for Universal Clipboard

Created skeleton UniversalClipboardManager and UniversalClipboardService
classes and register to system services.

Flag: android.companion.enable_universal_clipboard
Bug: 432068758
Test: flased to DUT and verified via adb shell dumpsys
universal_clipboard

Change-Id: Id3f14535d0debbb1305b4b7e83b3d9da02eadb65