Add format check utils method for bcradio metadata

Added format check method for AIDL broadcast radio HAL metadata in
AIDL utils library. Also corrected local variable name in
getMetadataString method.

Bug: 318868350
Test: atest broadcastradio_utils_aidl_test
Change-Id: I8220e2845143931e99b4e4da0e07c9cae585588e
diff --git a/broadcastradio/common/utilsaidl/include/broadcastradio-utils-aidl/Utils.h b/broadcastradio/common/utilsaidl/include/broadcastradio-utils-aidl/Utils.h
index 3ced685..25c96d0 100644
--- a/broadcastradio/common/utilsaidl/include/broadcastradio-utils-aidl/Utils.h
+++ b/broadcastradio/common/utilsaidl/include/broadcastradio-utils-aidl/Utils.h
@@ -143,6 +143,8 @@
 
 bool satisfies(const ProgramFilter& filter, const ProgramSelector& sel);
 
+bool isValidMetadata(const Metadata& metadata);
+
 struct ProgramSelectorComparator {
     bool operator()(const ProgramSelector& lhs, const ProgramSelector& rhs) const;
 };