RedirectConsoleStream: more debugging output

[scpeters]

🦟 Bug fix

Adds more console output to aid in debugging a failing test

Summary

A test has started failing recently on Windows:

• https://build.osrfoundation.org/job/gz_common-6-clowin/37/testReport/junit/(root)/RedirectConsoleStream/InlineHelpers/
• https://build.osrfoundation.org/job/gz_common-main-cnlwin/15/testReport/junit/(root)/RedirectConsoleStream/InlineHelpers/

This adds more debugging information by printing the name of the file if it already exists.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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