CBA-117 add a new page at the start of add solicitor details task for does the applicant have a solicitor

[patrickjfl]

Context

Jira ticket: https://dsdmoj.atlassian.net/browse/CBA-117

Changes in this PR

Adds a new page to the start of the solicitor details task, checking that the applicant has a solicitor. If they do, the referrer continues to the solicitor details. If not, the task is complete and they return to the task list.

Screenshots of UI changes

Release checklist

As part of our continuous deployment strategy we must ensure that this work is
ready to be released at any point. Before merging to main we must first
confirm:

Pre merge checklist

• Are any changes required to the e2e tests?
• If you've added a new route, have you added a new
  auditEvent? (see server/routes/apply.ts for examples)
• Are there environment variables or other infrastructure configuration which needs to be included in this release?
• Are there any data migrations required. Automatic or manual?
• Does this rely on changes being deployed to the CAS API?

Post merge

Once we've merged it will be auto-deployed to the dev environment.