Use `start` and `end` instead of `left` and `right` to be RTL ready

[adamkudrna]

This includes:

• List variants alignRight → alignEnd and alignLeft → alignStart
• (utilities: text-left → text-start, text-right → text-end)

[adamkudrna]

Let's skip the utilities, we can add responsive text alignment utilities like text-start and text-end later. text-left and text-right still have their place.