[IMP] types: make component generic types optional

In most cases, we just want Component<any, Env>. But since it was so
annoying to have always the type Env, we actually used
Component<any,any> everywhere.

With this commit, the generic types have a default (and their order is
swapped), so we can simply use Component in most cases, and
Component<Props> when we want to type the props.

src/misc/async_root.ts

@@ -10,7 +10,7 @@ import { xml } from "../tags";
  * from this coordination.  This is the goal of the AsyncRoot component.
  */
 
-export class AsyncRoot extends Component<any, any> {
+export class AsyncRoot extends Component {
   static template = xml`<t t-slot="default"/>`;
 
   async __updateProps(nextProps, parentFiber) {