Dump InputMethodManager#{mServedView, mNextServedView} for ime tracing

As CL[1] migrated {mServedView, mNextServedView} from ImeFocusController
to InputMethodManager and removed its proto dump, we add it back to
imputmethodmanager.proto to keep it tracked in winscope for debugging.
(And deprecate the original fields in imefocuscontroller.proto)

[1]:Ie3446e1d0f62c489195e31fc7f073020884d6cae

Bug: 244504062
Test: manual as following steps:
   1) rebuild rom image and winscope
   2) flash the rom and reboot the device
   3) run the built winscope and connect with the device
   4) start record trace by winscope page
   5) stop recording and verify {servedView, nextServedView} can be
      shown on the ImeClient Tracing panel.
Change-Id: I1ffb63a2e1e73591e7bf349d88e1e56728ab0953