feat: add responsive layouts for preview, search, user profile, login…

[chriswhong]

Reviewers: Please use the app using the mobile emulator at various sizes and see if you can find situations where the layouts break or other UI awkwardness shows up.

Closes #602

• Adds responsive layout for dataset previews, user profiles, search/search results, login/signup pages.
• Adds an appView prop to Head which injects a meta viewport tag with a fixed width for the "app" views (collection, history, run log, workflow editor. This causes them to appear "zoomed out" on mobile so they are still usable until a responsive layout can be designed)
• Adds a ScrollLayout layout component used for Previews, User Profiles, and Search where long-scrolling content is needed
• Renames PageWithFooter to FixedLayout and moves it to /features/layouts so we are more consistent with layout components
• Lots of little style tweaks to more closely match the mockups

[boandriy]

Hey @chriswhong , few things:

1. Is it supposed to look like that on bigger screens?
2. When I resize the page to be smaller then 1100 px I can see the side scroll