feat(Spotify): Add limited support for version 8.6.98.900 (last version that supports Kenwood and Pioneer car stereos) (#4750)

extensions/spotify/stub/src/main/java/com/spotify/useraccount/v1/AccountAttribute.java

@@ -0,0 +1,8 @@
+package com.spotify.useraccount.v1;
+
+/**
+ * Used for target 8.6.98.900. Class is still present in newer app targets.
+ */
+public class AccountAttribute {
+    public Object value_;
+}