i realized that my first attempt didn't properly parse empty use<> bounds, and then i forgot that type identifiers are also allowed, but now it should work properly i think.

theoretically speaking this syntax also allows const generic parameters, but i couldn't find a way to disambiguate between these two, so i just left those to be parsed as type_parameter. while it's impossible to disambiguate a use<N, T> and figure out if N is a type or a const parameter, it should be possible to take a good guess for something like use<LEN, Type>, but i don't know how to do that. (apparently that is already actually something that editors do in their own highlights.scm queries.)