wifi: Add APIs to set dual bands and dual channels

1. Add new APIs (get/set Bands/Channels) to support config the dual APs
mode.

2. Update the old API (get Band/Channel) to return smallest band/channel
which associated to the smallest band in dual bands setting.

The valid bands doesn't limit to 2GHZ & 5GHZ,
but the daul APs setting should be 2.4GHZ and 5GHZ on pixel.

PS: Also fix incorrect java doc link and descritpion.

Bug: 162686273
CTS-Coverage-Bug: 171179478
Test: atest FrameworksWifiApiTests
Change-Id: Id000a600c4786bd343e0ef69a7d489658f017037