contexthub: Pass target API version in new fields

Update default implementation to use the new fields defined explicitly
for passing in target CHRE API version information, rather than adding
this data into the reserved area.

Bug: 64852297
Test: run CHQTS on Nanohub, rebuild test app targeting 1.2 and confirm
      it's interpreted correctly
Change-Id: Id11f9b510a2d239d285436e119b7b8dbece4c5df