Make Regex Dictionary More Performant for Literals

[ColmBhandal]

String literal, non-regex matches are a special case of a regex that can be checked in O(1) time by simply storing them in a separate dictionary. Whenever someone adds a string literal to the regex dictionary i.e. RegexPatternDictionaryImpl, we should therefore store it in the backend in a separate dictionary of literals which we can check much more efficiently than looping through all regexes.