Avoid StackOverflowError in TypeUtils#resolveGenerics (#9858)

While the issue (#9855) is related to JDK21 and its new `getFirst` and
`getLast` methods in the `List`/`SequencedCollection` interfaces, the
current behaviour can in theory cause problems on JDK versions before 21
too.

With this fix the `TypeUtils#resolveGenerics` method falls back to
`TypeUtils#ensureBaseType` (already used method-level type variables)
when a type variable is used in the same class where it has been
defined.

This class for example, currently causes a `StackOverflowError`. With
this PR the error is avoided, and the `T` is resolved as
`java.lang.Object`:
```java
class BrokenClass<T> {
    public T getT() {
        return null;
    }
}
```

Fixes #9855

user/src/com/google/web/bindery/autobean/vm/impl/TypeUtils.java

@@ -207,6 +207,9 @@ public Type[] getActualTypeArguments() {
       Object genericDeclaration = variable.getGenericDeclaration();
       if (genericDeclaration instanceof Class<?>) {
         Class<?> declaration = (Class<?>) genericDeclaration;
+        if (declaration.equals(containingType)) {
+          return ensureBaseType(type);
+        }
         // could probably optimize, but would involve duplicating a bunch of
         // getParameterization's code
         Type[] types = getParameterization(declaration, containingType);