sf: Add basic implementation of onVsyncIdle

To adopt the new AIDL composer callback API, the patch changes the
architecture to pass HWC2::ComposerCallback directly in the
registerCallback function. The underlying implementations can use their
own bridge to adapt with different versions of callback APIs.

Bug: 194068871
Test: atest libsurfaceflinger_unittest
Change-Id: I08bcf481747f38805fb2527e18293585ede51554
diff --git a/services/surfaceflinger/DisplayHardware/AidlComposerHal.h b/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
index 6770017..374a436 100644
--- a/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/AidlComposerHal.h
@@ -63,7 +63,7 @@
     std::vector<IComposer::Capability> getCapabilities() override;
     std::string dumpDebugInfo() override;
 
-    void registerCallback(const sp<IComposerCallback>& callback) override;
+    void registerCallback(HWC2::ComposerCallback& callback) override;
 
     // Reset all pending commands in the command buffer. Useful if you want to
     // skip a frame but have already queued some commands.