Load routes and commands in the service provider's boot method

[xel1045]

This PR move routes and commands loading to the boot method to avoid incompatibility with other plugins (ex: #1170, #1149, #1125).

As described in Laravel's documentation, routes and commands should be loaded in the boot method to avoid loading things that are not ready yet:

As mentioned previously, within the register method, you should only bind things into the service container. You should never attempt to register any event listeners, routes, or any other piece of functionality within the register method. Otherwise, you may accidentally use a service that is provided by a service provider which has not loaded yet.

It seems a regression since PR #1055.

[pgrenaud]

Thank you! 🙏