Pass function to Bart inline in execute method

So you can now create an executor once and execute a few methods with it:

```csharp
// Create Bart executor
var executor = new BartExecutor()
    .WithOverrideForException<IOException>(someRetrySettings)
    .DontBubbleExceptions();

await executor.ExecuteWithAsyncBackoffs(someAction);

// Do some other stuff

// Call something again using the same executor
await executor.ExecuteWithAsyncBackoffs(someAction);
```

The idea is that when we implement logging, you can create the ``Bart`` object in your constructor, passing your logger, then call multiple things from it.

*Also works with synchronous version*