Row Selection might need another mode

[frykten]

Hello!

We have the use-case where we'd like the same selection as the checkboxSelectionMode="multiple" but on the row, meaning being able to click on a first row, selecting it, clicking another having both selected.

It is meant to be on : let toggle = event.ctrlKey || event.metaKey; (ember-tr/component.js)

Maybe we could add a property like let toggle = event.ctrlKey || event.metaKey || this.get('rowToggleMode');?