Fix ResolvableType raw class isAssignable checks

Fix `isAssignable` for `ResolvableType.forRawClass` so that it can be
used with types backed by a `TypeVarible`. Prior to this commit the
rawClass value was used, which wouldn't always work.

Closes gh-23321

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -1015,7 +1015,7 @@ public class ResolvableType implements Serializable {
 			}
 			@Override
 			public boolean isAssignableFrom(ResolvableType other) {
-				Class<?> otherClass = other.getRawClass();
+				Class<?> otherClass = other.resolve();
 				return (otherClass != null && (clazz == null || ClassUtils.isAssignable(clazz, otherClass)));
 			}
 		};