Contexthub HAL default implementation and service.

Adds the default context hub hal implementation and service.

Test: Context Hub GTS tests still pass.
Change-Id: I7416ce9ec8efca7f98d2bb63606f030f4e8c8ead
diff --git a/contexthub/Android.bp b/contexthub/Android.bp
index bbb3e4b..ba90f2c 100644
--- a/contexthub/Android.bp
+++ b/contexthub/Android.bp
@@ -1,4 +1,5 @@
 // This is an autogenerated file, do not edit.
 subdirs = [
     "1.0",
+    "1.0/default",
 ]