More control over Android project

## Feature Request

Dioxus seems to intend to abstract away android building completely by generating the whole project based on a template. Recently, support for overriding the AndroidManifest.xml was added so you can at least add permissions. But that's not enough if you need to interact with the system in more advanced ways.

For example, if you want to interact with [USB](https://developer.android.com/develop/connectivity/usb/accessory), you have to add non-asset XML files and handle certain intents.

It might also be useful to add java or kotlin code in case certain things are easier to handle there and not worth the effort to port to rust.

## Implement Suggestion

IMO, the current approach only works for applications that need (almost) no interaction with anything outside the WebView. Implementing more and more features of android manifests, resources etc in dioxus would probably never be features complete. I think it's best to allow using a manually written project directory instead of generating it.