Customizable image size presets

[ucupumar]

Currently there are only four available presets for image size. It will be nice if the preset is customizable.

• [x] Preference settings
• [ ] Add new option
• [ ] Remove new option
• [ ] Use the presets when creating a new image
• [ ] The UI should be adaptable based on as many the presets used
• [ ] Dealing with bake info data
• [ ] Old file versioning
• [ ] (Optional) Save the presets as a JSON file