GCS provider does not support Get-ChildItem's Filter property

[chrsmith]

Looks like we don't support Filter in Get-ChildItem. Unless we have a reason not to enable this, we probably should.

PS gs:\shopbot9000> Get-ChildItem -Filter *.png -Recurse items | Select Name,ContentType,Size | Out-GridView
Get-ChildItem : Cannot call method. The provider does not support the use of filters.At line:1 char:1
+ Get-ChildItem -Filter *.png -Recurse items | Select Name,ContentType, ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotImplemented: (:) [Get-ChildItem], PSNotSupportedException
    + FullyQualifiedErrorId : NotSupported,Microsoft.PowerShell.Commands.GetChildItemCommand