SF: Set up libscheduler headers

Start pulling Scheduler sources into a libscheduler target akin to
librenderengine and libcompositionengine.

Bug: 185535769
Test: Build
Change-Id: I8ee871cce96209c8c53601152501129b09c5e46f
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 3dc6d8b..5c9e1c5 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -135,8 +135,9 @@
         "libgui_mocks",
         "liblayers_proto",
         "libperfetto_client_experimental",
-        "librenderengine_mocks",
         "librenderengine",
+        "librenderengine_mocks",
+        "libscheduler",
         "libserviceutils",
         "libtimestats",
         "libtimestats_atoms_proto",