✨(frontend) add pdf block to the editor

[dakshesh14]

Purpose

Added an option for users to upload and preview PDF files in the editor. This PR addresses #348.

feat-pdf-upload.mov

Proposal

Added the option for users to upload and preview PDF files within the editor.

Description:

• When a user types '/' on their keyboard, they can find an option called "PDF," which allows them to upload or embed PDF files.
• A fallback is provided for browsers that do not support the 'embed' tag.

[dakshesh14]

Hey team, this is my first PR in the repo, and I <3 the project! I think there are a couple of areas that we could be improved in my PR and, I would love the maintainers' input on:

1. Using react-pdf or another library for better PDF preview compatibility and UX.
2. Changing the nginx config might not be acceptable, so I’m open to discussing alternatives.

Please let me know if I should look into these or if there are any other comments or suggestions. Once again, I love the project!

[AntoLC]

Hi, thank you for this nice PR!
I will catch some time this week to look at it correctly.