Clean up InputDispatcherPolicyInterface

- Remove RefBase from policy
- Store reference instead of pointer to policy
- Use references instead of pointers in parameters
- Use return values for all outputs for functions instead of passing an
  out parameter

Bug: 279927189
Bug: 245989146
Test: Presubmit
Change-Id: I31a2a3e8c67960020169ddfc59bc0a59f3e65c52