The default UDAF Method resolver. This resolver is used for resolving the
UDAF methods are used for partial and final evaluation given the list of the
argument types. The getEvalMethod goes through all the evaluate methods and
returns the one that matches the argument signature or is the closest match.
Closest match is defined as the one that requires the least number of
arguments to be converted. In case more than one matches are found, the
method throws an ambiguous method exception.