Support Markup Underline attributes

Underline attributes:
 - type
 - color
 - height
 - dash-gap
 - dash-width

How to apply it:
=========================================================================================
    TextLabel   textLabel = TextLabel::New();
    std::string exampleText =
      "START<u>only underline</u>THEN"
      "<u type='solid'>type is solid</u>THEN"
      "<u type='dashed'>type is dashed</u>THEN"
      "<u type='double'>type is double</u>THEN"
      "<u color='green'>color is green</u>THEN"
      "<u height='5.0f'>height is 5</u>THEN"
      "<u type='dashed' dash-gap='3.0f'>dashGap is 3</u>THEN"
      "<u type='dashed' dash-width='4.0f'>dashWidth is 4</u>THEN"
      "<u color='blue' type='dashed' height='4.0f' dash-gap='2.0f' dash-width='3.0f'>all attributes</u>END";
    textLabel.SetProperty(Dali::Toolkit::TextLabel::Property::TEXT, exampleText);
    textLabel.SetProperty(Dali::Toolkit::TextLabel::Property::ENABLE_MARKUP, true);
    textLabel.SetProperty(Dali::Toolkit::TextLabel::Property::MULTI_LINE, true);
=========================================================================================

This patch should be preceded by the patch below:
https://review.tizen.org/gerrit/c/platform/core/uifw/dali-toolkit/+/271187

Change-Id: I4ca7f11a1b0eeab51e90b48c3d1bbc470ad628e8