Consider generating R class bytecode directly.

Currently stub compiler generates R.java and other databinding classes for Kotlin compilation to work. The R.java in particular is compiled independently to allow not link it in runtime using `never_link`. This can be avoided by simply generating the R class as `.class` file using Java bytecode manipulation and pass it to Kotlin target via a `JavaInfo` provider.

On large modules R class compilation will not be a botteneck.