javac API change in Java 25 - Log.DiagnosticHandler

The internal javac Log.DiagnosticHandler API changes in Java 25: https://github.com/openjdk/jdk/commit/4890b74c048a1472b87687294c316ecfb324e4ba

This affects code in javacutil/src/main/java/org/checkerframework/javacutil/Resolver.java

https://github.com/typetools/checker-framework/blob/039b405c5d08c22324dbce3d45cfdd0ece567baa/javacutil/src/main/java/org/checkerframework/javacutil/Resolver.java#L241C5-L241C26

The diagnostic handler implementations switch from being static member classes to non-static inner classes, so e.g. new Log.DiscardDiagnosticHandler(log) needs to change to log. new DiscardDiagnosticHandler(log). Calling the constructor reflectively works with both versions, since either way it takes one argument for the log, whether that's the explicit parameter in Java < 25 or the synthetic enclosing instance parameter in Java >= 25.