Make VibrationEffect.WaveformBuilder public

Update WaveformBuilder to have a single method that adds transitions to
new sets of vibration attributes for a fixed duration. The parameters
are represented by a new type VibrationEffect.VibrationParameter, and
have two concrete types now: amplitude and frequency.

Update VibrationEffect.Composition API to add effects and repeating
effects, removing the repeat index parameter from WaveformBuilder.

Remove delay parameter from Composition in favor of a new method
addOffPeriod to make it less ambiguous when the delay is played in the
composition.

Bug: 203785430
Test: VibrationEffectTest
Change-Id: I40cbfaff2de3231378da7db6a2bc5c9252e6d8f8