Make WifiDeviceFilter.Builder.setSsid's arg @NonNull

Fixes: 143653080
Test: presubmit
Change-Id: Ia7715fe98c6a1f3a2d7e5cc702fadda1761e0f8e
(cherry picked from commit 133d12a7706183e045f4d7a98382c90fc7f74b68)
2 files changed