Add profile field 'descriptions' as tool-tips on the column names

[jamesrwelch]

In the normal profile editor, profile fields have little tool-tips that you can hover over to display the description of the profile field.

It would be helpful if this could happen on the bulk editor too.

[pjmonks]

Would need to check if the AgGrid component can render additional items to a header cell so that a tooltip for descriptions can be displayed. Otherwise this sounds simple enough.