[enhancement]: X:Y grid output

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Contact Details

_No response_

### What should this feature add?

An easy way to generate an X:Y layout, setting 2 parameters as the axes.

### Alternatives

The manual process involves grabbing the images and using an image editor to label axes and place thumbnails. This is slow, especially when experimenting with many variables.

### Additional Content

This would be especially helpful if different models or step counts or CFG (or other parameters) could be used for the axes. (This would require expanding the dynamic prompt functionality. In many ways, this can be thought of as an improvement to dynamic prompts and the dynamic prompt output UI.)

It might even be useful to add tabs (effectively a third axis) to the viewing UI. (For incremented seeds, for instance.)