Move withProgress and associated code to a separate file

[robertbrignull]

Thoughts: would it be clearer to move withProgress and associated code and types to a separate file, so it's not as linked to commandRunner?

I think this will make even more sense as we continue with the "typed commands" migration and essentially remove all usages of commandRunnerWithProgress, because tracking progress is now explicitly something that's done within the command rather than it appearing to be an intrinsic property of the command. I think separating the code will make it more clear that displaying/tracking progress is completely separate from running a command.

This PR is quite large because of the number of other files that import these types and methods. The only change here is moving code around, and a slight change to method documentation. I remove some bits saying to avoid using withProgress directly and to use commandRunner instead. I think with this code move it's clearer what each piece of code does, so this explanation isn't necessary.

Checklist

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.