Add configuration option for custom pattern for Tailwind color palette

[Dillon Kearns]

There is currently a hardcoded Regex that matches the default Tailwind v3 color theme names:

elm-review-html-to-elm/src/TailwindClass.elm

Line 124 in e2ed0f0

 (Regex.fromString "(\\w+)\\W(\\w+\\W\\d{2,3}|black|current|inherit|transparent|white)" |> Maybe.withDefault Regex.never) 

However, this will not catch colors from a custom Tailwind configuration if they don't follow the same pattern. One solution to support this would be to add an option in the configuration where the user can pass in a custom Regex string that will be used instead of the default when provided.

[Dillon Kearns]

See also discussion in #21