[dyno] implement discardWorseArgs disambiguation stub (chapel-lang#23813

)

This PR implements the `discardWorseArgs` function for Dyno
disambiguation. This PR is part 7 of a series of PRs that implement
disambiguation changes already in production from
chapel-lang#20528.

Also implemented in this PR are several supporting helper functions for
`discardWorseArgs`.

There is future work to implement rules ignoring the differences between
ref and value tuples.

[reviewed by @mppf - thanks!]