Encode hidl_version in each generated interface.

Each generated interface will have a constexpr encoding
the package version. Additionally, there's a client-facing
getInterfaceVersion() method; while for now it always returns
the static version, this is not always correct: in case this
interface has a transport that goes to a remote implementation,
the version needs to be retrieved from that implementation
instead. This depends on other changes and will be added with them.

Bug: 31297066
Change-Id: I15b7f5ccf2dbfa25acfd385c68e8ae1f3e782ade
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/FQName.h b/FQName.h
index a4a8565..b893bd7 100644
--- a/FQName.h
+++ b/FQName.h
@@ -116,6 +116,9 @@
             std::vector<std::string> *components,
             bool cpp_compatible) const;
 
+    std::string getPackageMajorVersion() const;
+
+    std::string getPackageMinorVersion() const;
 private:
     bool mValid;
     std::string mPackage;