Switch accounts in share/forward screens

From an user request:

If I share something to Deltachat, I would like to be able to choose which account to share it with then and there. As it currently is, I have to exit the share screen, open DC straightforwardly from the launcher, change accounts that way, and then try to share something to DC again.

It would also be good to be able to forward a message that was sent to one account, but forward it using a different account.