audio policy: LE audio broadcast routing policy

Implement routing policy for LE audio broadcast device.
LE audio broadcast device is only used if:
 - No call is active
 - Either MEDIA or SONIFICATION_RESPECTFUL is the highest priority active strategy
 OR the LE audio unicast device is not active

Bug: 213188698
Test: make
Change-Id: I47eb42066fe41c01867c35b1256241037583420b