analyze_code_size.py: provide option to further categorize specialized functions

[aschwaighofer]

The categorization can be viewed by using the -group-specializations command
line argument.

% utils/analyze_code_size.py -arch arm64e -group-specializations -categorize exe

Add -list-group-specializations to see the individual functions listed
under each group.

Current groups:

Swift.stdlib                class
Standard library specialization with one class type.

Swift.stdlib          class(dict)
Standard library specialization of a dictionary type with a single class type.

Swift.stdlib           foundation
Standard library specialization involving one foundation type (and possibly a
standard library type) or two foundation types.

Swift.stdlib    foundation, class
Standard library specialization where the the first type is from the
Foundation library and the second is a class.

Swift.stdlib                other
Standard library specialization with types other than the ones listed
here.

Swift.stdlib               stdlib
Standard library specialization involving standard library types only.

Swift.stdlib        stdlib, class
Standard library specialization where the the first type is from the
standard library and the second is a class.

[aschwaighofer]

@swift-ci Please test