BHV-14938: Added text directionality detection to placeholder and value properties

`placeholder` and `value` are used by InputHeader. Enabling detection on these properties means that text, when entered into an InputHeader can dynamically flip as needed by the input'd text.

Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>
Should a non-empty `value` string take directionality precedence here? It might be obscure, but I was thinking of the case (arguably, hanging off the edge case) where `placeholder` is later set to a value whose directionality differs from that of the current `value`. This would also allow us to remove the call to `valueChanged` in `rendered`. Let me know what you think!