Also check for home activity in BAL

Since checking for home process can fail if lancher has been killed but
we still want to allow launcher to start activities.

Bug: 189896361
Test: 1. Set app 1 as launcher, give PI for random activity to app 2
      2. With app 2 in fg, kill app 1
      3. Launch PI, verify it launches
Change-Id: Ia5eb5bfcf239b6dd2f732516edeac29a77c8a478