configstore: import configstore-utils as a header library

The android.hardware.configstore-utils library is no more built as a
static library but as a header only library.

This change applies this in building SurfaceFlinger.

Design doc: go/design-confighal
Bug: 35397068
Test: build, run on sailfish

Change-Id: I7d7abf3c87861bf7daa293af4e9d6841f854711e