perform fuzzy matching on invalid slugs?

[dmalan]

No description provided.

[cmlsharp]

This really belongs in push50, but since most folks are copying and pasting these anyway, not sure it adds much.

[cmlsharp]

check50 (for local anyway) now has this, but this would be quite expensive to do remotely. Not sure how this would be feasible for submit50 unless we presumptively assume cs50/problems and clone it locally even in the remote case.

[cmlsharp]

This has been implemented (for local check50). For remote it's a bit more complicated since we're more limited on what we can fuzzy match (if the org/repo is wrong we literally have no idea, and if the branch is wrong it could potentially be expensive to find all the valid branches/slugs).