[IMP] types: expose ComponentConstructor for typing purpose

We have been using this type in o-spreadsheet since https://github.com/odoo/o-spreadsheet/pull/1187
but the new typing file (https://github.com/odoo/owl/pull/1207) does not include it.
It would be useful to allow us to bump or version of owl witouht having to resort
to long aboslute paths (i.e. import from `@odoo/owl`and not
`@odoo/owl/dist/types/runtime/component@ everywhere).

src/runtime/index.ts

@@ -36,6 +36,7 @@ export const blockDom = {
 export { App, mount } from "./app";
 export { xml } from "./template_set";
 export { Component } from "./component";
+export type { ComponentConstructor } from "./component";
 export { useComponent, useState } from "./component_node";
 export { status } from "./status";
 export { reactive, markRaw, toRaw } from "./reactivity";