[Fast Pair] Add base FastPairNotificationBuilder

See nearby/discovery/ui/DiscoveryNotificationCompatBuilder.java

e2e video: https://photos.app.goo.gl/WawkcRm9eND3HfBb7

Test: -m
Bug: 247152236
Ignore-AOSP-First: nearby_not_in_aosp_yet
Change-Id: Ia03dd79417c0004f85427dba8d1e07848a6e4641
diff --git a/nearby/tests/unit/Android.bp b/nearby/tests/unit/Android.bp
index 9b35452..8a8aeab 100644
--- a/nearby/tests/unit/Android.bp
+++ b/nearby/tests/unit/Android.bp
@@ -29,6 +29,7 @@
         "android.test.base",
         "android.test.mock",
         "android.test.runner",
+        "HalfSheetUX",
     ],
     compile_multilib: "both",