LightGBM

[R-package] Make returned feature importances from lgb.importance() visible by default (#4194)

* Return feature importances as visible

Feature importances are returned as invisible. I don't get why would anyone want them invisible. This PR fixes it.

* Update R-package/R/lgb.importance.R

Thanks, didn't realize that, changed now.

Co-authored-by: James Lamb <jaylamb20@gmail.com>

Co-authored-by: James Lamb <jaylamb20@gmail.com>