Remove Roberta Dependencies from XLM Roberta Flax and Tensorflow models (#21047)
* Added flax model code
* Added tf changes
* missed some
* Added copy comments
* Added style hints
* Fixed copy statements
* Added suggested fixes
* Made some fixes
* Style fixup
* Added necessary copy statements
* Fixing copy statements
* Added more copies
* Final copy fix
* Some bugfixes
* Adding imports to init
* Fixed up all make fixup errors
* Fixed doc errors
* Auto model changes