add 'preview_imaginary_url', 'preview_imaginary_key','preview_format', 'webp_quality'

[JanisPlayer]

☑️ Resolves

I add 'preview_imaginary_url', 'preview_imaginary_key','preview_format', 'webp_quality'.

• Fix And I updated jpeg quality from 90 to 80 as it actually says in the code.

🖼️ Screenshots

[artonge]

Let's wait until nextcloud/server#38032 is merged, but this is perfect ❤️

[JanisPlayer]

I have already adjusted the doc a bit.
preview_imaginary_key
For the other previews options you could rename preview_format to preview_imaginary_format, because ImageMagick does not change anything.
Should there also be a mention of the key here?
Server Tuning

[szaimen]

@JanisPlayer please adjust the docs now that nextcloud/server#38032 is merged :)

[szaimen]

Looks good

[welcome]

Thanks for your first pull request and welcome to the community! Feel free to keep them coming! If you are looking for issues to tackle then have a look at this selection: https://github.com/nextcloud/documentation/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22