RTL is broken if the table is put inside another web component

[svanherk]

When d2l-table is placed inside another web component, the rtl rules are not being matched. Seeing this behaviour in d2l-evaluation-hub-activities-list and d2l-rubric-criteria-group (back to at least 10.8.10). I believe it's because we use [dir="rtl"] instead of :host(:dir(rtl)) in our css, but I haven't gotten a chance to test this theory yet.