Describe the bug
Forward slash / is not transparently converted to \ on windows. On windows powershell you can use a / and it's automatically translated to a backslash \. It would be nice if Nushell emulated this behavior as it makes working across windows and unix machines much more ergonomic.

To Reproduce
There seem to be a few corner case behaviors here

1. cd my/directory ends up with path C:\path\to\my/directory. cd succeeds but / gets preserved in path. Powershell will cd and transform the forward slash to a backslash.
2. cd my/dir<tab><tab> autocomplete will not complete if there's a forward slash on windows. Powershell completes this and converts it to a backslash.
3. ./myProgram will not run myProgram. This works on powershell.
4. Probably other ones I haven't noticed yet

Expected behavior
Forward slashes are transparently converted to back slashes on windows (or possibly otherwise follow powershell's behavior if there are corner cases?)

Configuration (please complete the following information):

• OS (e.g. Windows): Windows 10
• Nu version (you can use the version command to find out): 0.19.0
• Optional features (if any): default clipboard trash