Allow putting an invoice into "pending" without sending it

[CherryDT]

Is your feature request related to a problem? Please describe.
I would like to be able to put an invoice into the "pending" state (and even register payment on it) without necessarily sending it to the customer via email at that point. It's still possible to send it afterwards with the "Send" button that's still there, and in some cases I might not even want to send it through the system at all (but in some other way) but still have the correct customer email associated with the invoice in the system.

Describe the solution you'd like
A new button "Publish" that's doing the same as "Send" does except that it doesn't actually send the email.

Describe alternatives you've considered
It's possible to put a fake email of course, but a "proper" way would be better.