Provide editable AcroForms support in PDFViewer.

The current implementation of the Kendo PDFViewer depends on pdf.js, so the following should be taken into account:

https://github.com/mozilla/pdf.js/issues/7613

pdfViewer toolbar are always in english :

Bug report

The PDFViewer HTML helper incorrectly serializes the passed to its "File" configuration URL, when the URL has an ampersand(&) sign in it. In the output of the HTML helper, the ampersand is changed with its ASCII code - "\u0026"

• The issue is reproducible both in the UI for ASP.NET Core and UI for ASP.NET MVC suites.

Reproduction of the problem

1. Create an ASP.NET Core or MVC project
2. Paste the below code in it and run it
   @(Html.Kendo().PDFViewer() .Name("pdfviewer-test") .PdfjsProcessing(pdf => pdf .File("https://myrandomcomain.com/api/MyFolder/GetPDF?reference=xxxxxxxx&param1=0&param2=100&contentType=application/pdf") ) .Height(400) )
3. View the source of the opened page and see the generated Javascript code

Current behavior

The generated code is:
jQuery("#pdfviewer-test").kendoPDFViewer({"pdfjsProcessing":{"file":{"url":"https://myrandomcomain.com/api/MyFolder/GetPDF?reference=xxxxxxxx\u0026param1=0\u0026param2=100\u0026contentType=application/pdf"}},"height":400});

Expected/desired behavior

The expected result is
jQuery("#pdfviewer-test").kendoPDFViewer({"pdfjsProcessing":{"file":{"url":"https://myrandomcomain.com/api/MyFolder/GetPDF?reference=xxxxxxxx&param1=0&param2=100&contentType=application/pdf"}},"height":400});

Environment

• Kendo UI version: 2020.1.219
• jQuery version: x.y
• Browser: [all]

1. Allow the elastic behavior of the PDFViewer's mobile scroller to be disabled. Currently, when scrolling to the top or to the bottom, the document jumps and then immediately re-adjusts its position under the widget's header/bottom border.

2. Add the ability to manually scroll the document up/down with mousedown.

3. Add keyboard scrolling support.