[Resolver] Speed up searching
[Resolver] Speed up searching

1) even group_by isnt as good as manually enumerating -- it also gets rid of a bunch of convoluted logic
2) dont create SpecGroup objects just to throw them array
3) drop allocation of intermediary arrays

dilumnavanjana/bundler,bundler/bundler,mvz/bundler,RochesterinNYC/bundler,RochesterinNYC/bundler,dilumnavanjana/bundler,mvz/bundler,asutoshpalai/bundler,asutoshpalai/bundler,bundler/bundler