This matches the other saving-related methods for Gdk.Pixbuf
- `gdk_pixbuf_save_to_stream` was skipped for the auto-generated bindings (with the warning "Ellipsis parameter: hide and bind manually")
- `gdk_pixbuf_save_to_streamv` was in the generated bindings, but incorrect: the `option_keys` and `option_values` arguments had type `string` rather than `string[]`
Some Pixbuf, PixbufAnimation functions on Windows is exported with "_utf8" suffix.
I hid generated versions, copied and modified code to use "_utf8" on Windows.
Also hid "gdk_pixbuf_new_from_resource*", "gdk_pixbuf_animation_new_from_resource" because they are using GResources and we already have constructors for .NET resources.
