Read device name on connection with new LE devices

Android Bluetooth stack does not actively tries to find device name over
LE transport before pairing. It relies on name found during device
discovery. As a result, pairing dialog box for LE pairing without prior
device discovery don't show remote device name. This also happens if the
the remote device name was not found in the device discovery.

Test: mmm packages/modules/Bluetooth
Test: Manual | Start connectable advertising on DUT, initiate LE pairing
from another phone, pairing prompt on DUT must show the remote device
name
Flag: com.android.bluetooth.flags.name_discovery_for_le_pairing
Bug: 346365430
Bug: 355095011

Change-Id: Iea59ec9ba19148a5012cac8f3a5d2fd7304056fd