807: Authentication for UI in production mode

[chriswilty]

Description

Adds auth to the UI, in production mode.

When running the UI in dev mode (npm run dev) you shouldn't see the login. When running in preview mode (npm run build && npm run preview) you should see the login.

Resolves #807

Screenshots

Normal Zoom:

150% Zoom:

200% Zoom:

Notes

• A couple of accessibility weaknesses were identified, but unfortunately we don't have access to the Amplify components to correct them. The password show/hide button seems to work fine with NVDA, but it's not great with Narrator. Such is life.

Checklist

Have you done the following?

• [x] Linked the relevant Issue
• [ ] Added tests
• [x] Ensured the workflow steps are passing

[chriswilty]

FYI @pmarsh-scottlogic, @dhinrichs-scottlogic