Fix loss calculation in TFXXXForTokenClassification models (#15294)
* Fix loss calculation in TFFunnelForTokenClassification
* revert the change in TFFunnelForTokenClassification
* fix FunnelForTokenClassification loss
* fix other TokenClassification loss
* fix more
* fix more
* add num_labels to ElectraForTokenClassification
* revert the change to research projects
Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>