Stop requiring the namespace for datapacked registry elements in commands

There is currently a condition in SharedSuggestionProvider#filterResources that checks for the "minecraft" namespace when filtering elements for suggestions, requiring typing in the full namespace of a datapack element to find it. This is inconvenient and unnecessary, especially considering how long namespaces can get and that vanilla elements will still appear above any datapack elements with this condition removed (verified via mod). Please consider removing this condition to make using commands much easier for datapack/mod developers.