Bluetooth: Host: Add support for PAwR Sync

Adds API for Periodic Advertising with Responses - Scanner:
 - Synchronize to a PAwR train
 - Choose which subevents to synchronize to
 - Receive advertising reports from subevents
 - Send responses

The support is enabled by CONFIG_BT_PER_ADV_SYNC_RSP, and requires
a controller that selects CONFIG_BT_CTLR_SYNC_PERIODIC_RSP_SUPPORT.

Signed-off-by: Herman Berget <herman.berget@nordicsemi.no>