Only add promise icon if icon is provided in the SessionInfo.

- In some cases, SessionInfo is created without an icon until later on
  in the install process. This prevents promise icons with default Android
  logo from appearing.
- This will also prevent apps without a launching activity from appearing
  as a promise icon and then disappearing when the app is installed.

Bug: 135633159
Change-Id: I30adde8bf2cf583bffca8ed878f9cc20d6d41a13