Bluetooth: BAP: Add PAST Kconfig dependency for BASS

The broadcast assistant will only be able to send
BT_BAP_BASS_PA_REQ_SYNC_PAST if
CONFIG_BT_PER_ADV_SYNC_TRANSFER_SENDER is enabled.

Similarly the scan delegator will only set
past_supported = true if
CONFIG_BT_PER_ADV_SYNC_TRANSFER_RECEIVER is enabled.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>