Fix stevenage gov uk

[adam-prickett]

Fixes #1997

Stevenage has moved to Granicus and so this fix breaks existing implementations, instead requiring a UPRN over a postcode and property number.

The code was largely borrowed from highland_gov_uk

[5ila5]

Thanks for your contribution.

I just did some reformatting and ran the ./update_docu_links.py script

[jamesmyatt]

Thank you for this.

If highland_gov_uk also uses Granicus, is it worth trying to extract a common structure?

[adam-prickett]

Thank you for this.

If highland_gov_uk also uses Granicus, is it worth trying to extract a common structure?

Potentially, however Granicus appears to be a frontend for different services behind the scenes and so this implementation required an extra network call to obtain a token for the waste management service