Function scopeGuard

scopeGuard(fnOnDispose): Disposable
Creates a scope guard that will invoke it's lambda when the function terminates. The scopeGuard must be created and assigned to a variable marked with the using keyword.
```
using onExit = scopeGuard(() => console.log("Exiting scope"));
```
Parameters
- fnOnDispose: (() => void)
  The lambda to invoke when the object is being disposed.
  - - (): void
    - Returns void
Returns Disposable
A Disposable object that can be used to dispose the object.