Update APM XML deserializer for HAL V7

HAL V7 uses spaces instead of ',' and '|' for delimiting
elements in channel masks, sample rates, and flags lists.
The version specified in the APM XML has been updated
from '1.0' to '7.0' in order to reflect this.

Serializer classes were refactored to get access to
PolicySerializer class as a context which stores the
delimiters to be used.

Bug: 142480271
Test: m, check device boot
Change-Id: I7e765053e320b3789bc976e9905072c1eb476629