Add methods to add/remove the providers that should be hidden by this
provider. Also make a method to get a list of hidden providers.
This makes it possible to have multiple systems monitor the same devices
and remove duplicates.
Add a property to see all devices, even duplicate ones from hidden
providers.
* GstGlobalDeviceMonitor was renamed to GstDeviceMonitor
* Expand GST_MESSAGE_DEVICE to the full enum value names
* Correct the incorrect references to the GstDeviceProvider interfaces
* Describe caps arguments for gstcheck interface
* Add missing docs for GstNetAddressMeta and its add function
* Add docs for toc helper macros
* Avoid refering to GstValueList type as done elsewhere
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=732786
