This fixes the changes made in MDL-75047:
* Change `thisicondirection` langconfig string to a more specific one
like `questionicondirection`.
* Use existing direction string value `ltr` for the value of
`questionicondirection`. Also add a comment to at least provide some
form of documentation for it.
* Improve the logic for applying the horizontal flipping class for the
question icon:
- Check first if the icon is a question icon
- Flip the icon if `questionicondirection` is set to `rtl`.
b504d19c12