Support align attribute for paragraph tag in markup

<p align='center'> text </p>
Values: begin | center | end

//How to apply it:
textEditorMultiAlign.SetProperty(TextEditor::Property::TEXT, "text outside<p align='end'>Paragraph end</p><p align='center'>Paragraph center</p><p align='begin' >Paragraph begin</p><p>Paragraph property alignment</p>");
textEditorMultiAlign.SetProperty(TextEditor ::Property::ENABLE_MARKUP, true);
//The alignment on property level works on outside text or on a paragraph without the align attribute
textEditorMultiAlign.SetProperty(TextEditor::Property::HORIZONTAL_ALIGNMENT, Dali::Toolkit::Text::HorizontalAlignment::CENTER);

Change-Id: I3ccd6e6669a5887cdcbfa80be44998fd487e580c