chore: cleanup powershell code based on working on pwsh more

- Cleanup so it's less brittle and doesn't rely on psframework for basics.
- Pester migration to 5 broke the tests as is, so this instead focuses on making it just invoke pester.
- General tidy/update of the settings.

Author: sheldonhull

.gitignore

@@ -1,4 +1,3 @@
-
 # Created by https://www.toptal.com/developers/gitignore/api/macos,terraform,windows,powershell,linux
 # Edit at https://www.toptal.com/developers/gitignore?templates=macos,terraform,windows,powershell,linux
 
@@ -26,7 +25,6 @@
 # Icon must end with two \r
 Icon
 
-
 # Thumbnails
 ._*
 
@@ -111,7 +109,9 @@ $RECYCLE.BIN/
 
 # End of https://www.toptal.com/developers/gitignore/api/macos,terraform,windows,powershell,linux
 
-
 packages/
 artifacts/
 *.clixml
+.artifacts
+.cache/
+*.DS_Store