Test run in Sandbox

[doc-han]

Description

Allows users to run a workflow in a sandbox.

Questions

A few things aren't clear on this issue.

1. When a user is on a workflow in a project that has no sandbox. Do we create a new sandbox to be able to run in sandbox?
2. If the project already has a sandbox. There's high probability the sandbox has diverged(maybe doesn't contain this specific workflow anymore). Hence, how do we actually run the workflow in sandbox?

cc: @theroinaochieng @brandonjackson and maybe @josephjclark on suggestions

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I'm also thinking. Do we show this options when the project has a sandbox with the same workflow that hasn't diverged?

[josephjclark]

Why would you run in a sandbox without having made changes in a sandbox?

This feels like it's trying to solve the same thing as the "quick-spawn sandbox" in #3889

This needs clear scoping from Product team

[taylordowns2000]

Leave this out for now, yes I think it may have been referencing #3889

(Remember that this button actually is a "save & run" button... so you'd be saving your changes and running in the newly generated sandbox.)