Client side validation outline tests

These will be fleshed out, but as an outline spec what do people think?

Once we have the regex validator working, we can extend this to just to `email` type checking with a pre-defined regex.

_(This is also safe to merge as the tests are all empty and therefore pass)_
Cool yep OK. Struck me that we could find ourselves changing the range and forgetting to update the message accordingly but we can cater for that with the server side form helpers.