This PR fixes #94711

Adds an option to the git command error dialog to show the entire output from stderr in a readonly file. This is especially useful when a command fails due to a git hook as it lets the user see the reason for the failure without having to wade through unrelated output from the git extension.

To test:

1. Clone commit-hook-demo.
2. Install npm dependencies for commit-hook-demo.
3. Edit hello.js to introduce syntax error.
4. Attempt to commit changes via the “Git: Commit” command.
5. When the failure dialog appears click "Show Command Output”.