Adds default (mock) Context Hub HAL 1.2 impl

Also refactors common code.

Bug: 166845383
Test: Compile only (VTS test coming up in future CL)
Change-Id: Iae6cf09e2fffb854af61c29e6004ceb062a892b3
diff --git a/contexthub/1.2/default/android.hardware.contexthub@1.2-service.rc b/contexthub/1.2/default/android.hardware.contexthub@1.2-service.rc
new file mode 100644
index 0000000..936222a
--- /dev/null
+++ b/contexthub/1.2/default/android.hardware.contexthub@1.2-service.rc
@@ -0,0 +1,7 @@
+service vendor.contexthub-hal-1.2-mock /vendor/bin/hw/android.hardware.contexthub@1.2-service.mock
+    interface android.hardware.contexthub@1.0::IContexthub default
+    interface android.hardware.contexthub@1.1::IContexthub default
+    interface android.hardware.contexthub@1.2::IContexthub default
+    class hal
+    user context_hub
+    group context_hub