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: I6ded8898dea1e46475057236ae5c0e3e210502fd