Hide keyboard while the home button get pressed

For multi-client IME, launcher need to call hideSoftInputFromWindow() by
using the InputMethodManager instance that mapped the presented display
while its home button get pressed.

Bug: 120114697
Test: Manual verified that multi-client IME can be closed correctly.
Change-Id: I2edaa12d2e9c68d0e6dae5ca45f23abd9ab47acd