Add instrumentation for enter window mode with app handle drag CUJ.

See go/windowing-jank-coverage-one-pager for more details.

Bug: 339585205
Test: perfetto trace(https://screenshot.googleplex.com/AeiTJqrttW9J2Uz

)
Flag: NONE new perfetto instrumentation

Change-Id: I41611b16e2f716b2f66dc2840fbdb86d8dbc8029
Signed-off-by: Devarshi Bhatt <devarshimb@google.com>