GUI: editable output paths

[AhmetCanSolak]

This PR is adding a column on the images tab to expose the output path that will be used to write the resulting denoised image. This feature is requested by @li-li-github first but I think will be helpful to many. Initial design of the idea can be seen in the screenshot here:

One thing worth to mention, it is common to have users want to output everything into one specific folder location. We should try to enable an easy way to just set one output folder as well.

[li-li-github]

My original idea was that when I do batch processing, I wanted to output the denoised images to an independent folder because I thought that way is easier to organize things. I'd love to know if there's more needs for saving images in different path.

[AhmetCanSolak]

Here is a new approach suggestion:

• instead of having an output_path column we can have output_folder path
• this is pretty easy to populate for each new image and we can still let users to edit this field independently for each image
• we can allow users to update same column at once by double-clicking the header area?
• This way we will be matching the capabilities of CLI.

How do you feel about it @li-li-github ?

[li-li-github]

Ah, yeah this is exactly what I was imagining.