RSS feeds for WhatsApp Channels

### Category

Social Media

### Website URL

`https://www.whatsapp.com/channel/`
Example (a big channel): https://whatsapp.com/channel/0029Va3lbmz4inozK8EfxS0d

### Website description

Since the last year, the messaging platform WhatsApp features public channels, where admins can write to any of unlimited followers. Basically like what we already had on Telegram, which RSSHub supports already.

### What content should be included?

For the feed itself: the channel's name, description, and profile picture.
For the feed entries: all messages from a public channel should be necessarily included in the RSS feed. This means: their text (preferably, with the correct formatting), and any uploaded file or media (photos, videos, voice messages, but also other types of files within reason), as well as their sent date correctly set. Additionally, it would be nice if a custom field dedicated to listing the emoji reactions a message got was to be added in the RSS.

### Additional description

WhatsApp doesn't make the channels available for browsing on the website, and, I've checked, there is nothing of use inside the HTML or any loaded JavaScript. So, somehow, the data must be scraped by using the WhatsApp Web messaging client (`web.whatsapp.com`).

There are open-source libraries that work as alternatives to the WhatsApp Web client, but I'm not sure any of those support channels (yet), so I understand if this request comes out as tricky.
I also understand that you have many requests for RSS proposals and can hardly handle all of them, so I won't exclude the possibility of completing this proposal myself, but I'm creating this issue in the meantime, to see if there is any interest and maybe get the water flowing.

### This is not a duplicated rss request

- [X] I have searched [existing issues](https://github.com/DIYgod/RSSHub/issues) and [pull requests](https://github.com/DIYgod/RSSHub/pulls) to ensure this rss proposal has not already been requested