Initial ClockPlugin interfaces and ClockRegistry functions

Bug: 229771520
Test: Automated
Change-Id: I2bc8be56f9fb91734aa7d430270c3e9ad7328ed0
(cherry picked from commit c225417205b8f44086556681a10457ae4c7db917)
Merged-In: I2bc8be56f9fb91734aa7d430270c3e9ad7328ed0
5 files changed