uinput: add updateTimeBase command

The recent change to how event injections are scheduled causes problems
when a client waits a considerable time after a device registration
before sending a lot of events separated by delays. The long wait means
that many of the events get scheduled in the past, so they're all
injected at once, filling the kernel's buffers and causing events to be
dropped.

The updateTimeBase command allows the client to tell us that the long
delay is intentional, and that the following injections should be
scheduled relative to the current time, rather than the previous
injections or the registration.

[0]: change Ieaa4f2f06d5e0b7d13abc3afa474948996db7c0a

Bug: 330844071
Test: check for SYN_DROPPED events in the output of:
      $ adb shell getevent -lt
      while running the inking test:
      $ atest 'PlatformScenarioTests:android.platform.test.scenario.sysui.stylus.StylusInkingTest#writeText_appearsInShowcaseApp'
Change-Id: I31c596251e27149da16270a23f4f57e7bb8e3460