gd/hal: use the MGMT socket to interface with kernel

This patch uses the MGMT socket to interface with the kernel.
The purpose is to query the Bluetooth controller capabilities,
e.g., whether the Microsoft Extension is supported, etc. This
MGMT interface will be replaced by the sockopt/ioctl which will
be upstreamed to the kernel.

Bug: 246398494
Tag: #floss
Test: ./build.py --target test
Test: Manual test with next patch.

Change-Id: Ib2bd9d0ee4e8572a70935d68e68c52b260da2949