website: switch to embedpdf viewer

[jacksonrl]

link: https://github.com/embedpdf/embed-pdf-viewer

This is better than pdf.js. We need to be able to disable the tab bar though.

[jacksonrl]

I tested embedPDF and the WASM load time is too long in my opinion. It might be better to invest more in fixing the bugs in the current pdf.js based viewer. The main bugs are pinch-zooming and text selection.