Update footer/header from outside

[Ilan Schemoul]

Is your feature request related to a problem? Please describe.
I want to make a network request with curl using plenary however I do not want network request to slow everything down. I want this to be async.

Describe the solution you'd like
A command DashboardFooterUpdate DashboardHeaderUpdate so I can call that in the callback function.

Describe alternatives you've considered
It would be even better if dashboard could take an async function as footer/header but IDK if that's possible

[Ilan Schemoul]

#444 is merged