[Mirroring] MX DataGrid header label doesnt change alignment when setting layoutDirection style

Found in 4.5.0.14095

Steps to reproduce:
1. Compile and run attached MXML file.
2. Set layoutDirection to "rtl".

Actual Results:
Header contents arent moved to right edge of column.

Expected Results:
Header label should be right aligned.

Workaround (if any):
n/a