For ```brms``` model, return variables from all available source when calling ```insight::get_data()```

Hi, 

It would be really useful if you please return variables from both sources i.e., ```'source = "frame"``` and ```'source = "environment"```.

In addition, ```brms::brm()``` allow passing additional variables for post-processing via ```data2``` argument which is a named list. 

It would be greatly helpful if ```insight::get_data()``` return variables from all these three sources. 

Thanks 