Allow updating more fields in Update Entry API endpoint

[thallada]

• I have read this document: https://miniflux.app/opinionated.html#feature-request

Currently, the Update Entry endpoint only allows editing the title and content fields. I would like to change the endpoint to accept more optional fields (similar to the Update Feed endpoint) so I can edit more fields on entries via the API.

At minimum I think the editable fields should include: title, url, comments_url, published_at, content, enclosures, author, tags, starred and status.

I understand that there are existing endpoints for changing starred and status. However, I think adding these fields to Update Entry is still useful since Toggle Entry Bookmark only allows toggling the value vs. setting to a specific value and Update Entries is a bulk update whereas this would be a single entry update.

For context, I am developing a miniflux webhook handler that uses AI to process new entries and I would like to be able to set fields like comments_url and tags on entries via the API which is currently impossible through the API as far as I can tell. I think this keeps the spirit of minimalism because it allows offloading more features to external processes that integrate into miniflux through the API.

If the maintainer is open to this change, I can take a stab at implementing a PR for this.