Minor: Clippy router now uses types OnFormData and OnResponse.

[martinfrances107]

On my version of clippy ( 0.1.69 )

The '#allow' is not being recognised.

 #[allow(clippy::type_complexity)] on_response: Option<Rc<dyn Fn(&web_sys::Response)>>,

as I see this warning

warning: very complex type used. Consider factoring parts into `type` definitions
  --> router/src/components/form.rs:57:56
   |
57 |         #[allow(clippy::type_complexity)] on_response: Option<Rc<dyn Fn(&web_sys::Response)>>,
   |                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#type_complexity

I propose two new types,

type OnFormData = Rc<dyn Fn(&web_sys::FormData)>;
type OnResponse = Rc<dyn Fn(&web_sys::Response)>;

Each type is referenced twice in the code base.