[Sb refactor] Pull the WifiRepository interface out of the impl file (2/2)

Rename WifiRepository.kt -> WifiRepositoryImpl.kt for the impl's
definition. Also update the ktfmt_includes to ignore this file.

Test: WifiRepositoryImplTest
Bug: 238425913
Change-Id: I21f3259e9f86390da1a78d36f38c545199254e11
2 files changed