Rate limit user activity pokes in InputDispatcher

This rate limiting used to exist in PowerManager's JNI entry point.
Moving it to InputDispatcher helps us avoid building and sending the
request to the PowerManager JNI layer if the request is not going to be
sent to the Java layer.

We are also enabling configuration of this rate. Previously, a default
rate of 100ms per use-activity type was used. We have added an XML
config to allow overriding this value device-wide, for all user-activity
types. This helps devices adjust the rate as per their use cases.

Bug: 320499729
Test: atest InputDispatcherUserActivityPokeTests
Change-Id: I66fce1082e857b4d74b69e2d87d1a5fe1d9eb57c