[Feature Request] Allow regulator augment to determine which of the two inventories should be regulated

[Jack-McKalling]

Describe the feature

When adding a regulator augment to a puller/sender module etc, it adds a second button for toggling between Target and Destination inventory, below the current one that is for setting the amount. Currently when using the regulator to extract items, it only affects the other inventory and not the router's own buffer.

Being able to affect the router's own buffer would mean it becomes possible to stop pulling when the router has accumulated the set amount, or stop sending when it is about to go below the set amount.

Reasons why it should be considered

Currently it isn't possible to regulate the router's own buffer, so you can't for instance ensure it has exactly one item of a type and no more, as it will keep pulling more. Or if you want it to keep a certain amount ready in buffer, without oversending to elsewhere. This is very much within scope of the regulator augment, as it is also a form of regulation. Just from the other side of the same coin.

Additional details

Currently the regulator is affecting the destination inventory when inserting, and the target inventory when extracting. Different wording could be used to differentiate between the two inventories for the button, these words are just a suggestion. (alternatives are source, self, router, etc)