Zuzalu Confessions: Fix Login/Logout button flickers

[veronicaz41]

The 'Login'/'Logout' button flickers from 'Login' to 'Logout' if the user is logged in and refreshes the page. I would like it to not flicker, and say 'Logout' immediately if the user is logged in.

[veronicaz41]

proofcarryingdata/zupass#93 (comment)
I think we should extract this hook/state, along with the logic that determines whether to show the user a login or logout button into its own component called LoginLogout. To make it not flicker (the flickering i pointed out earlier), you could change

const [accessToken, setAccessToken] = useState<string | null>(null);
to

const [accessToken, setAccessToken] = useState<string | null>(() => window.localStorage.getItem("access_token") ?? null);
since localstorage is a synchronous API in web (thankfully)