Refine WindowInsets logs

- Add WM_DEBUG_WINDOW_INSETS ProtoLogGroup to use for logging
  general Insets logs in WM core.
- Refine InsetsSourceProvider#updateVisibility proto log format
  to add insets type information.
- Add InsetsSurceControl#toString to print control target info.

Bug: 197189357
Test: adb shell wm logging enable-text WM_DEBUG_WINDOW_INSETS
Test: atest ProtoLogImplTest \
            ProtoLogViewerConfigReaderTest \
            WmTests:ProtoLogIntegrationTest \
            LogDataTypeTest \
            protologtool-tests
Change-Id: I1f01ce4d9fe5cb17f7bd60a424689260682b1dfc