Expose LE advertiser address for easier PTS tests (1/6)

This patchset adds a hidden method getOwnAddress, that lets app with
BLUETOOTH_PRIVILEGED permission to lear their own addreess. This is done
exclusively for PTS tests.

Bug: 35147497
Test: manual
Change-Id: Iaf0f2fe0613de44b8430ac25e691d66a4ad44f8d
(cherry picked from commit 4bc4a441)