Rewrite for standalone zoneless components

[internettrans]

This is what I came up with working on the angular-microfrontends examples after upgrading to Angular 19. It doesn't yet support the custom single-spa routing location.

• single-spa props are used via signals now
• zonejs not supported in this version, might be added later
• schematics might need to be added for empty route, single-spa-props.ts
• no main.ts and main.single-spa.ts separation anymore, to match how react/vue operate where it's a single-spa application rather than a mixture of a standalone html web app and single-spa application. Single-spa isn't multi-spa
• Automatically add providers, rather than use getExtraProviders like in previous versions
• creating the application ref is done within single-spa-angular rather than inside of user code, to make it similar to other single-spa helper libraries. This allows single-spa-angular to automatically add providers as needed to the application's root component
• automatically detect selector for aot compiled root component.

[Greech]

Hi,
Is there a chance that this PR will be merged any soon?