Automatic selection of most recent gallery templates

This change allows the selection of the most recent gallery templates based on version when a publisher or template name or partial name is supplied.
This code does not affect dynamic parameters at all, follow same pattern that `GalleryTemplateIdentity` has for example. Something like
```csharp
if (!string.IsNullOrEmpty(GalleryApplicationName) &&
!GalleryApplicationName.Equals(galleryApplicationName, StringComparison.OrdinalIgnoreCase))
{
galleryApplicationName = GalleryApplicationName;
dynamicParameters = GalleryTemplatesClient.GetTemplateParametersFromGallery(
GalleryApplicationName,
TemplateParameterObject,
this.TryResolvePath(TemplateParameterFile),
MyInvocation.MyCommand.Parameters.Keys.ToArray());
}
```