This is a submission that aims to restore several "barely-used-due-to-bug" payload-related responses for all classes, as well as adding some to some classes that lackes responses.

As for CartMovingForwardDefense, see https://github.com/ValveSoftware/Source-1-Games/issues/4912

As I said before, some classes lackes specific responses. They are:
* Medic: CartMovingBackwardsDefenseMedic. I added the "Bomb is clear!" callout from MvM
* Demoman: CartMovingStoppedDefenseDemoman. I added the unused CartMovingForwardDefense responses.

Also, some classes have unused callouts that have been restored to add some variety. They are:
* Heavy: CartMovingForwardOffenseHeavy. I added a response from the map Helltower ("Push cart!")
* Heavy: CartMovingBackwardsOffenseHeavy. I added some of the unused responses from CartMovingForwardDefense ("Where is cart going?")
* Scout: CartMovingForwardOffenseScout. I added some of the unused responses from CartMovingForwardDefense.

Finally, some responses for the Scout simply don't work. I don't know why. I changed them to use a speak + soundscript.
All the changes have the "//new" comment on them.

I'm not including Engie because I have already submitted a fix for Engi ( https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2971113455 ). Pyro is next.