[SuperEditor][SuperTextField] Improve RTL support (Resolves #2472)

[angelosilvestre]

[SuperEditor][SuperTextField] Improve RTL support. Resolves #2472

We have some issues in RTL support:

• When typing in a SuperEditor with a RTL language, the caret always stays at the right side.
• When typing in a SuperTextField with a RTL language, the caret always stays at the right side and the text is left-aligned.

For SuperEditor, we have code to infer the text direction from the text itself, but we weren't passing the text direction down the TextComponent, and we were also not passing it to LayoutAwareRichText. As the result, the caret position is computed as if we are in LTR.

For SuperTextField, we weren't inferring the text direction from the text.

This PR makes the following changes:

• Allows passing the text direction to LayoutAwareRichText.
• Makes the SuperTextField's textAlign nullable, to choose the alignment based on the text direction, if the app doesn't enforce a text alignment.
• Applies a directionality to list items and tasks, to place the checkbox and list indicators in the right side when in RTL mode.