Integrate class proxy generation in AOT processing

[snicoll]

Now that class proxies can be generated at build-time and reused consistently (see #28115), we need to integrate that in our AOT processing. As part of this, the proper hint should be inferred so that the class can be discovered at runtime.

[snicoll]

This isn't complete without method invocation hints on the target class, as stated by @jhoeller:

I'm afraid that's the case since all the interceptor callbacks behind the proxy are Method-based, just like behind a JDK proxy. The naming arrangement is stable and in our control, so taking everything before the first $$ (for a class name to provide reflection for) should be a reliable way to handle it.

[snicoll]

Fixed by 9a1b7c5