Fix double backslashes in printed Windows paths

[itowlson]

Fixes #2158.

This changes user-facing messages (errors and prints; I skipped logs) to print paths correctly on Windows.

# Before
Logging component stdio to ".\\target\\..\\..\\dirmounttest\\.spin\\logs\\"
# After
Logging component stdio to .\target\..\..\dirmounttest\.spin\logs\

[rylev]

I'm happy with this change overall. We've had some debate about the right way to print paths, and I think this settles that debate. That being said, I do think we likely want to keep double quotes around paths as that usually makes it easier for readers to parse.