Update postcode field to GDS guidance

[terrysimpson99]

Describe the bug
This all about the 'Enter a postcode' field at: https://coronavirus.data.gov.uk/

1. The postcode field uses html5 validation. GDS guidance says: "Turn off HTML5 validation" and "To turn off HTML5 validation, add ‘novalidate’ to your form tags." (See https://design-system.service.gov.uk/patterns/validation/ )
   Go to https://coronavirus.data.gov.uk/
   Go to the 'Enter a postcode' field
   Type 'sw1a'
   Press the magnifying glass icon
   System responds with a coloured exclamation mark and "Please match the format requested."
   I would expect an error message like 'Enter a UK postcode'

Screenshot

2. The postcode field does not accept redundant characters. Users add these and sometimes can't see what's wrong (particularly if they are spaces which are invisible, of course). GDS guidance says: "It is easier for users if you accept and ignore unwanted characters. This is better than rejecting the input and telling a user they’ve not provided a valid postcode. You should allow postcodes that contain upper and lower case letters, no spaces, additional spaces at the beginning, middle or end and punctuation like hyphens, brackets, dashes and full stops."
   Go to https://coronavirus.data.gov.uk/
   Go to the 'Enter a postcode' field
   Type ' SW1A 0AA' [preceding space], or 'SW1A 0AA' [double space in middle], or 'SW1A-0AA' [hyphen], or 'SW1A 0AA.' [full stop], or 'SW1A 0AAA' [extra character]
   Press the magnifying glass icon
   System responds with a coloured exclamation mark and "Please match the format requested."
   I would expect each of the above examples to produce a result as if the user had typed 'SW1A 0AA'

HP laptop
Windows 10.0.19042
Chrome Version 87.0.4280.141 (Official Build) (64-bit)

Additional context
We addressed this issue by stripping all non-postcode characters and then putting space 3 characters from end. We did this prior to validation. See: https://github.com/hmrc/voa-bar-xml-frontend/blob/master/app/journey/PostcodeValidator.scala

Trying to help. Keep up the good work

[xenatisch]

This is not bug. For compliance queries, please get in touch via the email provided on the website.