Bluetooth: Add hidden API to get current user of HID Device (1/3)

Bug: 69136526
Test: test with apps using HID Device profile
Change-Id: If0e49840257c877c975c2da176a08e613668cbc3
(cherry picked from commit 347ef4099e0d2b1334efd22e6ca7d5cc5464b4eb)
1 file changed