Copies as alternative to Symlinks

[sningo]

Symlinking is a great option, especially on Linux. However, on Windows, creating symlinks often requires administrative privileges. To address this, this PR introduces a copies option as an alternative. While less performant, it provides a reliable solution. Some users may even prefer this approach, as copied dependencies can be versioned, making it easier to review PRs that include library changes.

[jacebrowning]

Thanks for the suggestion! Would you consider making this a fallback for links if permissions are denied? I'm not sure I want to add another parameter for this right now.

[sningo]

Thank you for checking. Actually not as an automatic fallback or so, but as another option. In our Team we've been using copies for a while. Apart from the windows reason, there was also the requirement to have all the certification critical code in one repo. Thanks to the copies we could still have the generic code in an external repo, making it easier to be used in others.