Key similarity checker

[thclark]

In cases where a strand key (or a property key in a schema) is missing or absent, use levenshtein distance or fuzzy matching to determine whether a similar key is given in the input, then add a suggestion to the warning or error, e.g.:

Strand "credentials" is not present, but twine file contains key "crdntials" . Did you mean "credentials"?

[thclark]

Can also be used as a twine validation check. We can't exclude additional fields using the twine schema (in case people need to add their own metadata in the twine, or we want to add more strands), but we could apply this additional check after the twine has been read.