[WifiSetup] Make dialogs immersive

Added a dialog specific applyImmersiveFlags method that adds
immersive flags without the LAYOUT_ flags. The LAYOUT_ flags causes
the dialog to not resize when IME is visible, and the dialog doesn't
need to be drawn under the navigation / status bars anyway.

Bug: 17759269
Change-Id: I0186e85d9f398af73c511b1a5ec6e83febe97f83
3 files changed