[Feature Request] Add "Create New Folder" to file open prompt.

[amozeo]

Original issue is https://github.com/pop-os/cosmic-files/issues/391

I found it necesssary in some cases to create a new directory in a "Open file" dialog, however this dialog lacks that feature. Examples include:

• Opening and creating a folder in vscode when starting a new project
• Picking a custom location for a new collection in bruno, when that location doesn't exists yet
• Basically anything when the open dialog expects a directory, but that directory doesn't exists yet

In all of those cases I have to create a new directory through other means, for example by opening a new window of cosmic files and navigating to a place where I want a new directory.

cosmic-files revision: 9455d6f08476395b7e2c455d73e4420b05c9fe4b

[iamkartiknayak]

Needs context menu entry, one can still create new folder in this dialog with Ctrl + Shift + N shortcut