LambdaBeanELResolver#getType should return null if the resolved property is read-only

EL 5.0 Spec Change:
Explicitly document that ELResolver.getType() must return null if either the ELResolver or the resolved property is read-only.

We do not check if the property is read-only in our overridden method.

Our code:
https://github.com/apache/myfaces/blob/main/impl/src/main/java/org/apache/myfaces/el/resolver/LambdaBeanELResolver.java#L47-L58

This was discovered in our tests as RC4 disabled USE_LAMBDA_METAFACTORY.