Bluetooth: Add framework for Microsoft vendor extension

Micrsoft defined a set for HCI vendor extensions. Check the following
link for details:

https://docs.microsoft.com/en-us/windows-hardware/drivers/bluetooth/microsoft-defined-bluetooth-hci-commands-and-events



This provides the basic framework to enable the extension and read its
supported features. Drivers still have to declare support for this
extension before it can be utilized by the host stack.

Signed-off-by: Miao-chen Chou <mcchou@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>