Create user preferences page

[HuxleyBerry]

Create the user preferences page. Initially, the page should look something like this:

Then once the user has pressed the edit button, the page should change its appearance to something like this:

See the figma for what the page should look like on desktop. I suggest replacing the text which says "Home >> User Preferences >> Edit Profile" with simply "Preferences" and making that appear in both states (i.e. editing and viewing) of the page.

Also, if the user edits their avatar or bio, the values in the user store should be modified appropriately. That should cause the user's displayed avatar and bio to change too. In the future, we'll need to check with the backend first before making those changes, but that is outside the scope of this issue, so for now just leave a comment in the spot in the code that would need to be done.

[github-actions]

Branch issue-116-Create_user_preferences_page created!