Automatically register middleware in "web" group

[reinink]

This PR updates the service provider to register the Inertia middleware in the web middleware group, instead of the global middleware stack.

The primary motivation for this change is because the current session reflashing behaviour does not work right now, and that's because the middleware is run before the session is started. Moving it to the end of the web middleware group fixes this.

inertia-laravel/src/Middleware.php

Lines 20 to 22 in 0a9af99

	if ($request->hasSession()) {
	$request->session()->reflash();
	}

Also, it feels odd to register the Inertia middleware globally, when it should really only run on the web endpoints, and not, for example, on the api endpoints.