Each interface gets its own module named ${Interface}Binding. Structs, enums, and callbacks
continue to use the root module of the binding file. If there is only one interface in the
file, we generate reexports for several public APIs and types so that existing DOM implementations
don't need any modifications. When multiple interfaces exist, the reexported names get the interface
name prepended (eg. FooWrap instead of Wrap).
As part of this work, stop glob-importing all DOM types in every generated binding and start generating
more targeted lists of relevant types based on the methods, members, etc. of WebIDL types that are in use.
Some interfaces like Node, CharacterData and HTMLTableCellElement are never
instantiated directly, only their descendant interfaces are. Those are marked
with [Abstract] to set their type_id to None instead of having dummy values
in the TypeId enums.
