Adding PDF Shortcut

[MarionMoseby]

Issue

Adding PDF Shortcut #522

Fixes #522

Description

Adds the latest version of pdf-js (from: https://mozilla.github.io/pdf.js/) to the static/js folder, and the embed-pdf shortcode (maybe could be renamed to pdf?) to layouts/shortcodes. This shorcode was mainly taken from anvithks/hugo-embed-pdf-shortcode, as is implied to preserve copyright. Maybe an issue should be opened in his repo to let him now? (not necessary but nice)

Test Evidence

A minimal reproducible example can be reproduced like so:

1. Create a test post in toha/content/posts/test/
2. Fill index.md with:

---
---

{{< embed-pdf src="/posts/test/test.pdf" >}}

3. Add a test pdf in toha/content/posts/test/test.pdf
4. Issue: hugo serve

The result should be like so:

[MarionMoseby]

There are a ton of useless: Merge branch 'hugo-toha:main' into main commits, but I dont know how to remove those :/

[MarionMoseby]

One possible improvement could be adding a "download" button to the top menu
To-Do: Write post in toha-guides with usage
Another note: I replaced the url: parameter with a src: parameter, as it seemed more consistent with the other shorcodes.

Are these 3 things ok?

[hossainemruz]

Thanks you @MarionMoseby. Can you please add a guide for the short code?.