User profile and settings

[kgilles]

After user auth flow(issue #13) has been added to the UI we can expand on the user features and create the user profile and settings pages.

[slickplaid]

See #79 (review) for some issues (item 1, 2, and 3 in that list) that should be addressed in this feature that were left out of the initial #13 feature completion.

The initial load of user settings should ideally not rely on a client side call to /api/v3/site to retrieve user preferences and make page updates after the page has finished loading. Ideally this should be server-side rendered, or if we want to defer full SSR until things are more complete, support skeleton loading indicators on the content and rely on the client to initially fetch the content (initial load of the page would be without data, then hydrated).

Either way, re-hydration based on user settings or changes to the user settings should be supported, so it might make sense to progressively improve rather than jumping to full SSR unless warranted.

If needed we could split this out into two or more issues (create and define user settings and page, allow page to be dynamic when adjusting user preferences, support SSR for logged in user's user preferences) to be addressed individually if this proves to be too much for a single issue.

[kgilles]

Depends on sublinks/sublinks-api#398