`MarkdownEditor` suggestions break when querying by 3 or more characters

[iansan5653]

We noticed an odd bug in Projects today (https://github.com/github/memex/issues/12620) -- when the user types more than 2 characters to filter the suggestions list, the suggested values become completely incorrect. For 2 or fewer characters, the suggestions make sense, but something seems to break after that. I was able to reproduce this by adding a few more suggestions to the MarkdownEditor story.

In this list, "GitHub" should be first and "mnl" shouldn't appear at all:

[iansan5653]

I've found out that this is because fzy.js (the fuzzy filtering library we are using) returns Infinity if the length of the match item is less than the length of the query (and the shortest username a user on GitHub can have is 3 characters).