LibWeb: Add missing includes

This remained undetected for a long time as HeaderCheck is disabled by
default. This commit makes the following file compile again:

    // file: compile_me.cpp
    #include <LibWeb/HTML/CrossOrigin/CrossOriginOpenerPolicy.h>
    // That's it, this was enough to cause a compilation error.

Likewise for most other files touched by this commit.

Userland/Libraries/LibWeb/Forward.h

@@ -454,6 +454,7 @@ class URLSearchParamsIterator;
 }
 
 namespace Web::Bindings {
+class CallbackType;
 class LocationObject;
 class OptionConstructor;
 class RangePrototype;