Support SIGTSTP and task posting. (#331)

- Add support for SIGTSTP:
https://github.com/ArthurSonzogni/FTXUI/issues/330
This

- Add support for task posting.
This allows folks to defer function execution, and execute it directly
below the main loop. The task are executed in a FIFO order.

CHANGELOG.md

@@ -18,6 +18,10 @@ Element gaugeDown(float ratio);
 Element gaugeDirection(float ratio, GaugeDirection);
 ```
 
+#### Component
+- Support SIGTSTP. (ctrl+z).
+- Support task posting. `ScreenInteractive::Post(Task)`.
+
 2.0.0
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