Fix usings and copyright headers

[rjmholt]

No description provided.

[andyleejordan]

Were you able to use tooling for this?

[rjmholt]

Not for the copyright headers, but I was for the usings

[andyleejordan]

Not for the copyright headers

Hm, I must be misremembering. It looks like I did it via find-replace (so that's kinda tooling, eh?) in #1466.

[rjmholt]

I remember writing a PS script that did it for some repo...

Wait, just remembered. It's here.

[andyleejordan]

Um @rjmholt we also had a copy of that at some point in time: https://github.com/PowerShell/PowerShellEditorServices/blob/244954343c227d1a5cb766b727d46259516bd325/scripts/AddCopyrightHeaders.ps1

...

Did I delete it?!

[andyleejordan]

Yup: #1473

With a note: "The copyright header script will be replaced"

And I think I was planning to do it with the .NET Analyzers (or something) and still am! There's so much left to do there.

[rjmholt]

do it with the .NET Analyzers

The nice thing about the script is that it can operate on any filetype