Plumb PHY settings down to native layer

Currently there is no support for actually setting the physical
layer used for scans, despite the fact that this is available as
an option in scan settings.

Add that support.

Bug: 228268706
Bug: 326249470
Test: atest LeScanningManagerExtendedTest
      atest ScanManagerTest
Change-Id: Ie7f7f5282a8cd78ea742fe2fb8c58df87f1649f0