[NUI] Minimize system settings API calls in Text

[NUI] Minimize system settings API calls in Text

Each text component's call to the system API takes a lot of time.
Especially for FontType, initialization of FontConfig occurs natively and consumes most of the time.

This patch updates through static classes only when a specific value is needed.

TODO: manager should handle all events.

Signed-off-by: Bowon Ryu <bowon.ryu@samsung.com>