Add two properties in `ProviderInfo` class: `ItemSeparator` and `AltItemSeparator`.
On windows, the default values for those two properties are `ItemSeparator = '\'` and `AltItemSeparator = '/'`.
On unix, the default values for those two properties are `ItemSeparator = '/'` and `AltItemSeparator = '\'`.
Registry provider is the only exception, both properties for it have the value `\`.
Based on standard practices, we need to have a copyright and license notice at the top of each source file. Removed existing copyrights and updated/added copyright notices for .h, .cpp, .cs, .ps1, and .psm1 files.
Updated module manifests for consistency to have Author = "PowerShell" and Company = "Microsoft Corporation". Removed multiple line breaks.
Separate PR coming to update contribution document for new source files: #6140
Manually reviewed each change.
Fix#6073
This restructuring moves tests to a directory name which matches the module
in which the cmdlet resides which should improve the discoverability of a
specific test.
For tests which are not about cmdlets in a module, new directories have been
created to make those tests easier to find as well
Steve Lee