connection_manager: Add initial support for target announcements

Extend connection manager to handle target announcement.
Goal:
1. if there are multiple user for single device and at least one of them
is expecting to use target annoucements, then only scan filtering for
targeted annoucements shall be used
2. When user requested targeted annoucement usage is removed, and there
are other users interested in background conneect, then device shall
be added back to the accept list

Bug: 248340126
Test: atest BluetoothInstrumentationTests
Test: atest --host  net_test_gatt_conn_multiplexing
Tag: #feature

Change-Id: I00f30dcccbdb3d8712d49f15c9d8d7bae60663f6