Rename when ingesting dataset with duplicate feature names

**Background**
Woodwork doesn't support having multiple features (columns) with the same name. We chose this because we want users to be able to use the feature name as the index into the woodwork metadata, and into the underlying data.

Pandas allows multiple columns to have the same column index, and/or multiple rows to have the same row index.

**Proposal**
When the user provides a dataframe which contains multiple features, woodwork should rename the duplicated columns and warn the user that this has been done for them.

@angela97lin @rpeck @gsheni @BoopBoopBeepBoop FYI