Update header from outside

[juansalvatore]

Is your feature request related to a problem? Please describe.
It would be great to have an option to update the header based on some autocommand or async update.

Describe the solution you'd like
A command to force the refresh of the header

Describe alternatives you've considered
maybe a method that accepts a string as argument for the new header or the same setup options passed to the initialization to refresh the dashboard.

Additional context
I only found this related feature request #438 but from what I saw it only added the option to refresh the footer.