Update theme for new request process

[crowbot]

• [x] The theme customises request/new, so needs to get the new parameters on the call to get similar requests.
• [x] The tab order on the signup page needs to be updated.

[garethrees]

For the redesigned new request process https://github.com/mysociety/alaveteli/issues/1526

[garethrees]

Done in https://github.com/mysociety/sobanukirwa-theme/tree/use-with-alaveteli-0.21.0.0