[Looker] [Feature Request] PNG Visualisation Export - Image Size Specification in the UI

[Dawid]

I like using PNG export of visualisation for content creation of many types. However in the dialog:

I'm missing ability to specify the size. We can do it by changing the URL : https://test.cloud.looker.com/render/process/l/2000/1400/query-visualization but it would be nice to have these settings in the UI.