Add option for node local tasks in toolbar

I liked the way the feature was implemented here better, so I've rebased the code to get a new patch that would apply.

Re-rolled for rc4

Maybe move this to a separate module instead of re-rolling? The issue is marked as Closed (won't fix).

Can confirm thatt patch #49 works with rc4.
I understand DieterHolvoet. But we have several projects at our company that are using gin + gin toolbar + local tasks at this moment, and we need to be able to update them. Changing the patch to a rc4 compatible patch in composer is the easiest way to do that for us at the moment, until a tried and tested separate module for this actually exists.