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

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

Bug: 351956025
Test: perfetto trace(https://screenshot.googleplex.com/5jhRfjqhoyNLend)
Flag: NONE new perfetto instrumentation
Change-Id: I2c3c689a723d7003173d190a29d2f69321f21661