Rearrange Navbar links to decide Contributions positioning

[svileshina]

PR #821 added Contributions button to the navbar when user is in p2p but logged out:

And then it prompted a conversation about the rearranging of this (and other) buttons in the navbar to denote priority without causing confusion when buttons change locations based on mode/logged in status. The following is from discussions from the PR:

We talked some about rearranging these. Our concerns were:

arranging buttons so items of higher priority or higher usefulness stand out more, which changes depending on context
if someone logged in trying is to give instruction to someone not logged, it should be easy without the logged in person having to memorize which buttons are and are not the same for the logged out person
having order be consistent and predictable
understanding that most logged in users won't be spending much time if any looking at what a not logged in person sees
Because of all these concerns, we agreed to revisit how to balance them later