Emit toString functions for all types.

* toString() is mainly for debugging purposes only.

* For HIDL internal types (hidl_string, hidl_vec, etc.)
  toString() is found in ::android::hardware::details.

* For a user defined type
  android.hardware.foo@1.0::IFoo.Type,
  toString() is found in ::android::hardware::foo::V1_0.

* For bitfield<::anroid::hardware::foo::V1_0::T>
  that gets translated to the underlying
  numeric type of T, it doesn't make sense to override toString().
  A templated toString() function for each user-defined HIDL enum \
  is introduced into the same namespace; call it with
    using namespace ::android::hardware::foo::V1_0;
    toString<IFoo::MyEnumType>(value);

Test: hidl_test and look at the output of logcat

Bug: 33459772

Change-Id: I70eee018e31d700bf1376334276dbd343af5615f
diff --git a/ScalarType.cpp b/ScalarType.cpp
index fbd127c..9b6c0c3 100644
--- a/ScalarType.cpp
+++ b/ScalarType.cpp
@@ -211,6 +211,13 @@
     handleError(out, mode);
 }
 
+void ScalarType::emitHexDump(
+        Formatter &out,
+        const std::string &streamName,
+        const std::string &name) const {
+    out << streamName << " += toHexString(" << name << ");\n";
+}
+
 void ScalarType::emitJavaFieldReaderWriter(
         Formatter &out,
         size_t /* depth */,