WifiServiceImpl: allow setWifiApConfiguration to return false

The api for setWifiApConfiguration allows for config saves to return
false, but the implementation is void. This CL allows the API to
actually return a boolean indicating success/failure and adds an ap
specific validation check.  This CL also adds unittests.

Bug: 67601382
Test: frameworks/base/wifi/tests/runtests.sh
Test: frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Test: manually update ap config in settings and verify save
Test: wifi integration tests
Change-Id: If09fffc66415d9d3d3f4f386aaff98b0a103d2f4
2 files changed