Use method meta-data in getTypeForFactoryMethod

[philwebb]

Update AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod to
use already loaded method meta-data when deducing the type of a factory
method.

[jhoeller]

In the meantime, the cached factory method return type is a ResolvableType which takes a generic method signature into account. It seems generally sensible to immediately resolve the Method handle there (rather than inferring the declared return type from the ASM metadata) since the actual Method is subsequently introspected for other purposes as well. Resolving the ASM-declared type name first (which involves a ClassLoader call) and then the full Method handle shortly thereafter (which comes with the resolved return type Class as well as a potential generic declaration) is not likely to provide a performance benefit within the current container bootstrap arrangement anymore.