WELD-2758 Proxies for non-public class-based beans should reside in bean's package if possible

[manovotn]

https://issues.redhat.com/browse/WELD-2758

[manovotn]

This seem to work fine although I noticed we might want to skip some cases (i.e. built-in beans).
While debugging it, I noticed that for instance our built-in bean for jakarta.transaction.UserTransaction is a package private class org.jboss.weld.module.jta.UserTransactionBean.
Using the code in this PR means we will try to define this bean directly into Weld's JTA module package.
This seems wrong but OTOH anything for jakarta.* or java.* package would end up in custom package (org.jboss.weld.generated.proxies) anyway 🤷

Note that for the attached test case, we'd normally try to place the proxy in the api package, where we detect the interface.

EDIT: I've added a condition to skip built-in beans

[mkouba]

Looks good.