Handle Emoji clustering for cursor handling

Handle Emoji clustering for cursor handling

Checked cases:
  - cursor movement (arrows): it works fine
  - line-breaking: it works fine
Resolved cases:
  - deletion: this patch handled delete cases when the cursor is before or after Emoji
    :: Before: when use delete key and cursor is before Emoji
    :: After: when use backspace key and cursor is after Emoji
  - Emoji layoutted at the end of line: this patch handle the below scenario
    1) When there is Emoji contains multi unicodes and it is layoutted at the end of line (LineWrap case , is not new line case)
    2) Try to click at the center or at the end of Emoji then the cursor appears inside Emoji
    3) Example:"FamilyManWomanGirlBoy 👨‍👩‍👧‍👦"

 Sample code to test:
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    TextEditor textEditor = TextEditor::New();
    textEditor.SetBackgroundColor(Dali::Color::GRAY);
    textEditor.SetProperty(Dali::Toolkit::TextEditor::Property::TEXT, "AB👨‍👩‍👧‍👦AB👩🏻‍🔬B👨‍👩‍👧‍👦AA☪︎B☪️AB");
    textEditor.SetProperty(Actor::Property::ANCHOR_POINT, AnchorPoint::TOP_LEFT);
    textEditor.SetProperty(Dali::Actor::Property::POSITION, Vector2(10, 30));
    textEditor.SetProperty(Dali::Actor::Property::SIZE, Vector2(100, 100));
    textEditor.SetProperty(Dali::Toolkit::TextEditor::Property::ENABLE_MARKUP, true);
    textEditor.SetProperty(Dali::Toolkit::DevelTextEditor::Property::LINE_WRAP_MODE, Dali::Toolkit::DevelText::LineWrap::WORD);

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Change-Id: I6d142c58c5cdef5e900404cca8b777a02c8488d1