TransactionAspectUtils contains a number of methods useful in
retrieving a bean by type+qualifier. These methods are functionally
general-purpose save for the hard coding of PlatformTransactionManager
class literals throughout.

This commit generifies these methods and moves them into
BeanFactoryUtils primarily in anticipation of their use by async method
execution interceptors and aspects when performing lookups for qualified
executor beans e.g. via @Async("qualifier").

The public API of TransactionAspectUtils remains backward compatible;
all methods within have been deprecated, and all calls to those methods
throughout the framework refactored to use the new BeanFactoryUtils
variants instead.