Add parallelism and copy-on-write links to Robocopy task

[erikmav]

• Use the CopyOnWrite library and an action block to greatly speed up artifact copies. Use parallelism settings similar to those in the Microsoft.Build.CopyOnWrite SDK and allow turning off CoW linking with a task setting.
• Fix an overcopying bug where the same source:destination pair would be copied multiple times.
• Don't copy files onto themselves (seen in occasional cases).
• Linearize same-destination copies from different sources.
• Update major version of Artifacts.
• Unify on 'DisableCopyOnWrite' property for Copy and Artifacts
• Migrate CoW SDK Copy task to use CoW package for clone file compat checks.
• Fix possibility of under-copying different-cased files/paths on Linux by varying path comparers by OS. NOTE: Did not update the CoW Copy task, and MSBuild itself seems to use IgnoreCase in most cases. Need feedback here.

[erikmav]

@jeffkl I don't see how to increment the Microsoft.Build.CopyOnWrite SDK version - ideally the newer 0.3.3 CopyOnWrite should be used in a new version of that package.

[jeffkl]

@jeffkl I don't see how to increment the Microsoft.Build.CopyOnWrite SDK version - ideally the newer 0.3.3 CopyOnWrite should be used in a new version of that package.

Would just setting this to 1.1 be enough? https://github.com/microsoft/MSBuildSdks/blob/main/src/CopyOnWrite/version.json

The build number automatically increments for each commit but I manually adjust the minor version for feature releases.

[erikmav]

I think 1.0.NewBuildNumber would be fine as long as it gets published after this commit. Not sure how that works for this repo.

[erikmav]

One other note - tests ran successfully on a Dev Drive with CoW capability.