Previously, the LibWeb bindings generator would output multiple per
interface files like Prototype/Constructor/Namespace/GlobalMixin
depending on the contents of that IDL file.
This complicates the build system as it means that it does not know
what files will be generated without knowledge of the contents of that
IDL file.
Instead, for each IDL file only generate a single Bindings/<IDLFile>.h
and Bindings/<IDLFile>.cpp.
Many wpt test on trusted-types relay on this class being defined to even
begin the test as it declares some event handlers.
This is not really an implementation but the most basic setup needed to
run the tests.
