Fixes date field validation message presents in reverse order

[MattOz-CDS]

Overrides the validateDate method in the Datebase class so that date validation error messages display a UK style date format e.g dd-mm-yyyy.
https://github.com/localgovdrupal/localgov_forms/issues/67

[finnlewis]

Just discussing in Merge Tuesday with @MattOz-CDS @Adnan-cds @ekes

Thinking it would be safer to namespace the date format to something like:

localgov_forms_uk_html_datetime

This would keep it namespaced and reduce the chances of conflicts with existing date formats.

[andybroomfield]

Is html_date an actual specified date format?

So maybe not calling it html date as thats for the spec.
It would be nice if this was configurable for form builder (not essential for this PR though).

[MattOz-CDS]

Is html_date an actual specified date format?

So maybe not calling it html date as thats for the spec. It would be nice if this was configurable for form builder (not essential for this PR though).

Alright Andy, thanks for sharing your thoughts on this. The name choice was inspired by the names of other date formats that are present in our Drupal install. I assumed that this was an established naming convention, so that's why I went with it. I'm happy to change it, that's no problem. What would you recommend? I also agree that it should be configurable for site builders. I'm happy to do that as well, its just that I was looking for a quick win because this change is urgently needed.

[andybroomfield]

I don't know, it was a question! :-)
localgov_forms_date_datetime is good.