wifi: API Review: API changes to SoftApConfiguration.Builder

1. enableClientControlByUser should be renamed
to setClientControlByUserEnabled.
2. setShutdownTimeoutMillis(int) should take a long,
same for getter. Millisecond durations are always long.
3. Separate setClientList into two methods

Bug: 150855680
Test: atest frameworks/base/wifi/tests/
Change-Id: Ib065993748e186790290d3e50f4f28a09146fd65