Show exporting the chart to PDF using the Drawing API

[Stamo-Gochev]

See https://bit.ly/3iMN92v (note: private repo)

The current example at: https://github.com/telerik/blazor-ui/tree/master/common/pdf-jpg-export-js

shows exporting the grid to PDF, but the chart is exported to JPG only.

Exporting it to PDF will not work as a separate instance of the Drawing API is instantiated by loading another script: https://github.com/telerik/blazor-ui/blob/ffb971add2408f318cdf3241e2e72de8ffb1707f/common/pdf-jpg-export-js/PdfExportJS/Pages/_Host.cshtml#L35 which prevents the PDF processing to detect the correct DOM elements.