Use android.util.IndentingPrintWriter instead

This only replaces
  com.android.internal.util.IndentingPrintWriter
with
  android.util.IndentingPrintWriter
in InputMethodManagerService since the former was already deprecated
and the later is what's currently recommended [1].

Other than that there is no behavior change.

 [1]: Idd2bfa027733ef384b5a676866a89fb3c35b06cb
      f800b70d

Bug: 171827834
Test: presubmit
Change-Id: I176f9da16be8953b6fea6e391c88a32dd2746f49