uktrade/directory-sso

(Please add a sentence or two explaining the context of this PR. Reviewers can go to the ticket for detail.)
CONTEXT: This changeset adds/removes/updates [summary of feature/area/code] so that [summary of benefit].

_Tick or delete as appropriate:_

### Workflow

- [ ] Ticket exists in Jira https://uktrade.atlassian.net/browse/TICKET_ID_HERE
- [ ] Jira ticket has the correct status.
- [ ] A clear/description pull request messaged added.

### Reviewing help

- [ ] Explains how to test locally, including how to set up appropriate data
- [ ] Includes screenshot(s) - ideally before and after, but at least after

### Housekeeping

- [ ] Added all new environment variables to Vault.
- [ ] Cleaned up old feature flags
- [ ] Upgraded any vulnerable dependencies.
- [ ] I have updated security dependencies
- [ ] Python requirements have been re-compiled.

### Merging

- [x] This PR can be merged by reviewers. (If unticked, please leave for the author to merge)