Signed-off-by: John Howard <jhoward@microsoft.com>
If fixes an error in sameFsTime which was using `==` to compare two times. The correct way is to use go's built-in timea.Equals(timeb).
In changes_windows, it uses sameFsTime to compare mTim of a `system.StatT` to allow TestChangesDirsMutated to operate correctly now.
Note there is slight different between the Linux and Windows implementations of detecting changes. Due to https://github.com/moby/moby/issues/9874,
and the fix at https://github.com/moby/moby/pull/11422, Linux does not consider a change to the directory time as a change. Windows on NTFS
does. See https://github.com/moby/moby/pull/37982 for more information. The result in `TestChangesDirsMutated`, `dir3` is NOT considered a change
in Linux, but IS considered a change on Windows. The test mutates dir3 to have a mtime of +1 second.
With a handful of tests still outstanding, this change ports most of the unit tests under pkg/archive to Windows.
It provides an implementation of `copyDir` in tests for Windows. To make a copy similar to Linux's `cp -a` while preserving timestamps
and links to both valid and invalid targets, xcopy isn't sufficient. So I used robocopy, but had to circumvent certain exit codes that
robocopy exits with which are warnings. Link to article describing this is in the code.
