Support frontend status readiness query.

The caller could use it to check whether frontend status is ready to
read or not.

Bug: 171540820
Test: atest VtsHalTvTunerTargetTest
Change-Id: I65521aacd8afe824342ad0b24f7d89006ceb5851
diff --git a/tv/tuner/aidl/vts/functional/FrontendTests.h b/tv/tuner/aidl/vts/functional/FrontendTests.h
index 537c419..1746c8e 100644
--- a/tv/tuner/aidl/vts/functional/FrontendTests.h
+++ b/tv/tuner/aidl/vts/functional/FrontendTests.h
@@ -102,6 +102,7 @@
     void scanTest(FrontendConfig frontend, FrontendScanType type);
     void debugInfoTest(FrontendConfig frontendConf);
     void maxNumberOfFrontendsTest();
+    void statusReadinessTest(FrontendConfig frontendConf);
 
     void setDvrTests(DvrTests* dvrTests) { mExternalDvrTests = dvrTests; }
     void setDemux(std::shared_ptr<IDemux> demux) { getDvrTests()->setDemux(demux); }