Incorporating ONNX Support into Brain Tumor Segmentation Example

[ctongh]

Is your feature request related to a problem? Please describe.
In our development endeavors, we've leveraged the robust capabilities of the MONAI library, facilitating rapid progress in our projects. However, our usage scenario spans across diverse platforms, prompting us to opt for ONNX to store our model parameters and utilize ONNX Runtime for inference.

Describe the solution you'd like
Upon reviewing the monai/tutorial repository, we found a lack of examples incorporating ONNX or similar technologies. Thus, we've crafted a simple example based on the brats_segmentation_3d to demonstrate the disparate output results of different models.

We're keen to contribute this code snippet to monai—happy to contribute!

[Kbinn]

I'd like to ask you how it's going. I'm currently working on a project that has this exact need. Thanks.