Refactor interfaces in com.itextpdf.kernel.pdf.tagutils package

Replaced IAccessibleElement+AccessibilityProperties with AccessibilityProperties abstract class;
Old AccessibilityProperties class is replaced with DefaultAccessibilityProperties implementation of abstract class;
Changed most of the API that concerns tag roles in order to make it work with java strings;
Introduced separate StandardRoles class for possible role constants;
Introduced PdfStructureAttributes wrapper for structure attributes.

DEVSIX-1236

Autoported commit.
Original commit hash: [4237de6b10]

Author: yulian-gaponenko

itext.tests/itext.forms.tests/itext/forms/FormFieldsTaggingTest.cs

@@ -44,6 +44,7 @@ source product.
 using iText.Forms.Fields;
 using iText.Kernel.Geom;
 using iText.Kernel.Pdf;
+using iText.Kernel.Pdf.Tagging;
 using iText.Kernel.Pdf.Tagutils;
 using iText.Kernel.Utils;
 using iText.Test;
@@ -189,7 +190,7 @@ public virtual void FormFieldTaggingTest07() {
             PdfButtonFormField pushButton = PdfFormField.CreatePushButton(pdfDoc, new Rectangle(36, 650, 40, 20), "push"
                 , "Capcha");
             TagTreePointer tagPointer = pdfDoc.GetTagStructureContext().GetAutoTaggingPointer();
-            tagPointer.MoveToKid(PdfName.Div);
+            tagPointer.MoveToKid(StandardRoles.DIV);
             acroForm.AddField(pushButton);
             pdfDoc.Close();
             CompareOutput(outFileName, cmpFileName);

itext.tests/itext.kernel.tests/itext/kernel/pdf/PdfStringTest.cs

@@ -50,6 +50,7 @@ source product.
 using iText.Kernel.Pdf.Canvas;
 using iText.Kernel.Pdf.Canvas.Parser;
 using iText.Kernel.Pdf.Canvas.Parser.Listener;
+using iText.Kernel.Pdf.Tagging;
 using iText.Kernel.Pdf.Tagutils;
 using iText.Kernel.Utils;
 using iText.Test;
@@ -192,8 +193,8 @@ public virtual void WriteUtf8AltText() {
             PdfCanvas canvas = new PdfCanvas(page);
             TagTreePointer tagPointer = new TagTreePointer(pdfDoc);
             tagPointer.SetPageForTagging(page);
-            tagPointer.AddTag(PdfName.Div);
-            tagPointer.AddTag(PdfName.Span);
+            tagPointer.AddTag(StandardRoles.DIV);
+            tagPointer.AddTag(StandardRoles.SPAN);
             //  2001: A Space Odyssey (Космическая одиссея)
             tagPointer.GetContext().GetPointerStructElem(tagPointer).SetAlt(new PdfString("2001: A Space Odyssey (\u041A\u043E\u0441\u043C\u0438\u0447\u0435\u0441\u043A\u0430\u044F "
                  + "\u043E\u0434\u0438\u0441\u0441\u0435\u044F)", PdfEncodings.UTF8));
@@ -274,8 +275,8 @@ public virtual void WriteUtf8ActualText() {
             PdfCanvas canvas = new PdfCanvas(page);
             TagTreePointer tagPointer = new TagTreePointer(pdfDoc);
             tagPointer.SetPageForTagging(page);
-            tagPointer.AddTag(PdfName.Div);
-            tagPointer.AddTag(PdfName.Span);
+            tagPointer.AddTag(StandardRoles.DIV);
+            tagPointer.AddTag(StandardRoles.SPAN);
             tagPointer.GetContext().GetPointerStructElem(tagPointer).SetActualText(new PdfString("actual", PdfEncodings
                 .UTF8));
             canvas.BeginText();

itext.tests/itext.kernel.tests/itext/kernel/pdf/PdfStructElemTest.cs

@@ -342,7 +342,7 @@ public virtual void StructElemTest07() {
             span1.AddRef(span2);
             span1.SetPhoneticAlphabet(PdfName.ipa);
             span1.SetPhoneme(new PdfString("Heeeelllloooooo"));
-            @namespace.AddNamespaceRoleMapping(PdfName.Span, PdfName.Span);
+            @namespace.AddNamespaceRoleMapping(StandardRoles.SPAN, StandardRoles.SPAN);
             document.GetStructTreeRoot().AddNamespace(@namespace);
             page.Flush();
             document.Close();