Wildcard for unmatched key-value pairs

[epage]

#106 kicked off support for #92 but the match logic doesn't have a way to say "I don't care about any other key-value pairs".

How should this be represented?

[epage]

If we support [..] within keys, then "[..]": "{...}" would mean "match all keys and all values for those keys".

With this route, we'd need a "match most specific first" approach to not have the wildcard consume all