unsplat component::Linker::func_wrap args (#5065)

* component::Linker::func_wrap: replace IntoComponentFunc with directly accepting a closure

We find that this makes the Linker::func_wrap type signature much easier
to read. The IntoComponentFunc abstraction was adding a lot of weight to
"splat" a set of arguments from a tuple of types into individual
arguments to the closure. Additionally, making the StoreContextMut
argument optional, or the Result<return> optional, wasn't very
worthwhile.

* Fixes for the new style of closure required by component::Linker::func_wrap

* fix fuzzing generator

crates/fuzzing/src/generators/component_types.rs

@@ -158,7 +158,7 @@ macro_rules! define_static_api_test {
                 .func_wrap(
                     IMPORT_FUNCTION,
                     |cx: StoreContextMut<'_, Box<dyn Any>>,
-                    $($param_name: $param,)*|
+                    ($($param_name,)*): ($($param,)*)|
                     {
                         log::trace!("received parameters {:?}", ($(&$param_name,)*));
                         let data: &($($param,)* R,) =