Merge android.util.imetracing into com.android.internal.inputmethod

This CL renames classes related to IME tracing as follows

 * android.util.imetracing.ImeTracing
     => com.android.internal.inputmethod.ImeTracing
 * android.util.imetracing.ImeTracingClientImpl
     => com.android.internal.inputmethod.ImeTracingClientImpl
 * android.util.imetracing.InputConnectionHelper
     => com.android.internal.inputmethod.InputConnectionProtoDumper

Other than those renamings, there should be no observable chagnes.

Fix: 175761228
Test: presubmit
Test: Manually verified that IME tracing still works
Change-Id: I6518d946e1832037f240f57aa900d3447083f1fa