Fixes #3777

Changes:

• Added a visible upload button for logged-out users
• Display login-required state instead of hiding the feature

I have verified that this pull request:

• [✔] has no linting errors (npm run lint)
• [✔] has no test errors (npm run test)
• [✔] has no typecheck errors (npm run typecheck)
• [✔] is from a uniquely-named feature branch and is up to date with the develop branch.
• [✔] is descriptively named and links to an issue number, i.e. Fixes #123
• [✔] meets the standards outlined in the accessibility guidelines