p2p: add annotation for WifiP2pConfig.Builder public API

Bug: 126614191
Bug: 126702130
Test: Unit tests - atest FrameworksWifiTests
Test: Unit tests - atest FrameworksWifiApiTests
Change-Id: I5ca97e26c0f8509a35c72b422c754771a9c50e1a
2 files changed