Frontend: Hide Elements based on Login

[ansengarvin]

ui_auth_lock.mp4

How to test

Since there are new dependencies, you must do the soft_restart shell command to install and refresh the packages. To test the changes, you should log into to the website with email "test" and password "test".

What this PR does

• Stores the user's login status in a svelte store, allowing the website to keep track of whether the user is logged in
• Automatically checks if cookie exists when browser is refreshed; If it does, sets svelte store to login
• Deletes authentication cookie if user visits login page (e.g. if user logs out), and also clears stored login status
• Changes login button text between "login" and "logout" depending on user login status
• Hides / shows upload button based on user login status
• Hides / shows edit button based on user login status
• Automatically alerts the user and redirects them to home if they manually type in the URLs to the upload or edit pages
• Changed the test user email and password both to "test", to make it easier to test.

Not addressed in this PR, but still needs to be done

• Frontend needs to be changed to send authentication tokens to backend from the cookie
• Backend needs to be changed to verify the authentication tokens prior to executing restricted requests (POST, PATCH, DELETE)
• Unauthorized access to upload/edit pages should redirect to a 401 Unauthorized page (not yet implemented) instead of home
• Some notification element should be created to better communicate to the user that they are logged in
• We should probably create some sort of basic user profile (so users can know which account they are logged into)

New Dependencies

• svelte-store

Closes #165
Closes #166

[xnought]

svelte store is already included in the svelte library, I'll remove this

[xnought]

Super excellent! Let's merge it