Migrate to a common timer class

This change pulls in sdeventplus and uses the timer implementation as
a drop in for the currently included timer.

Tested:
    Unit tests still build but are not currently running. Manually
    tested this change on a zaius machine and made sure timers went off.

Change-Id: I2808196581fc766843931403b83fead16926b0ae
Signed-off-by: William A. Kennington III <wak@google.com>
11 files changed