Make items usable via the inventory screen

__This is WIP, this pull request is meant as a discussion platform and a means to demonstrate how the behaviour could be implemented.__

This allows the player to double click directly on items within their inventory and it would execute actions associated with that item.
```
// Example
class AGM_myItem: ItemCore {
  class AGM_Action {
    condition = "true"; // the condition under which to allow the action
    statement = "hint 'item is good';"; // code to execute when double clicking on the item
  };
};
```
__Potential issues caused by this__
- Player unfamiliarity
- Confusion around where to find actions, some actions occur via the inventory screen, others via interaction menu
- Less visible context for what an action will do (fixable via adjustment of descriptionShort text or potentially other means)
- No interaction with items underwater (BIS bug/feature/short sight)

__Known issues currently in this implementation__
- Clicking cancel when selecting trigger will open the interaction menu (due to not overriding a ton of behaviour when implementing this code)

__Gains__
- Potential for intuitive interaction with the game (double click on Clacker to use it, double click on magazine to repack, etc.)
- Clears the Interaction menu for interactions that simply cannot be assigned directly to an item