hidl_test_java interfaces: use generic interfaces

In places where we are passing interfaces, pass around
android.hidl.base.IBase to give flexibility to the test implementation,
specifically in order to avoid passing local binders to Java process,
which is a disabled feature.

Bug: 169369810
Test: atest hidl_test hidl_test_java
Change-Id: I7721a6ec7e72b96915a0dc66aa8e75c327032d1f
diff --git a/tests/baz/1.0/IBaz.hal b/tests/baz/1.0/IBaz.hal
index 7855446..8be1d61 100644
--- a/tests/baz/1.0/IBaz.hal
+++ b/tests/baz/1.0/IBaz.hal
@@ -94,7 +94,7 @@
         int8_t[7] array;
         string oneString;
         vec<string> vectorOfStrings;
-        IBase dummy;
+        interface iface;
     };
     oneway doThis(float param);