Support cancelling when searching for dependencies

まだ誰も着手していません。

I use the quick create option to create a new environment in a very large worksapce folder (lots of folders and files, basically my dev folder).
The progress window has been going on for a long time,

I think we should support adding `Cancel` button for such actions, as these aren't compulsory, i.e. users need to be able to exit from this
My only solution was to exit VS Code and create the env manually.