Protect IME tracing IPCs with CONTROL_UI_TRACING

With this CL, the following IPCs start requiring callers to have
CONTROL_UI_TRACING permission [1].

 * IInputMethodManager#startImeTrace()
 * IInputMethodManager#stopImeTrace()

Note that the following shell commands

 adb shell cmd input_method tracing start
 adb shell cmd input_method tracing stop

should not be affected by this CL because those commands are directly
handled by

 * IInputMethodManager#onShellCommand(),

which has been guarded with calling UID check [2].

 [1]: Ibdeb38dc9a066cb8ed2904adcdac29014b166526
      2ad02a38
 [2]: If87189563ccaacd4f9c666bab4f9ad08a9343084
      b8d240fa

Bug: 34886274
Bug: 172444310
Bug: 237316307
Test: make RunSettingsRoboTests ROBOTEST_FILTER="WinscopeTraceTest"
Test: Manually verifies as follows.
  1. build aosp_coral-userdebug and flash it.
  2. Go to System Settings.
  3. Enable Developer Mode.
  4. Go to Developer Options.
  5. Tap "Quick settings developer tiles"
  6. Enable "Winscope Trace"
  7. Pull down the quick settings drawer then Tap Winscope Trace.
  8. Tap some edit field to show AOSP Keyboard.
  9. Pull down the quick settings drawer then Tap Winscope Trace.
 10. adb root
 11. adb shell ls -al /data/misc/wmtrace/
 12. Make sure that tracing files are saved there.
Test: Manually verifies as follows.
  1. build aosp_coral-userdebug and flash it.
  2. adb shell cmd input_method tracing start
  3. Tap some edit field to show AOSP Keyboard.
  4. adb shell cmd input_method tracing stop
  5. adb root
  6. adb shell ls -al /data/misc/wmtrace/
  7. Make sure that tracing files are saved there.
Test: Manually verifies as follows.
  1. build aosp_coral-userdebug and flash it.
  2. adb root
  3. adb shell cmd input_method tracing start
  4. Tap some edit field to show AOSP Keyboard.
  5. adb shell cmd input_method tracing stop
  6. adb shell ls -al /data/misc/wmtrace/
  7. Make sure that tracing files are saved there.
Change-Id: Iaee7be9fb5066664b283a64273bf8685ba966046