Add new option for CURLOPT_HTTPPROXYTUNNEL

Describe the bug

I'm running FreshRSS in a small k8s cluster. By default, everything works fine besides some feeds that fail due to cloudflare challenges. I've had good experiences with just using a vpn for those, so I'm trying to use my vpn over gluetun as a proxy like this https://github.com/FreshRSS/FreshRSS/issues/3965 :

  'curl_options' => 
  array (
CURLOPT_PROXYTYPE => CURLPROXY_HTTP,    
CURLOPT_PROXY => 'gluetun-9d6e4ac1.download.svc.cluster.local',    
CURLOPT_PROXYPORT => 8888,    
  ),

However, I then get the error below, which looks similar to https://github.com/FreshRSS/FreshRSS/issues/3965

A feed could not be found at `https://hnrss.org/frontpage`; the status code is `200` and content-type is `` [https://hnrss.org/frontpage] 

When trying to use curl directly in the pod, it works:

curl --proxy gluetun-9d6e4ac1.download.svc.cluster.local:8888 https://hnrss.org/frontpage -v
*   Trying 10.43.86.62:8888...
* Connected to gluetun-9d6e4ac1.download.svc.cluster.local (10.43.86.62) port 8888 (#0)
* allocate connect buffer
* Establish HTTP proxy tunnel to hnrss.org:443
> CONNECT hnrss.org:443 HTTP/1.1
> Host: hnrss.org:443
> User-Agent: curl/7.88.1
> Proxy-Connection: Keep-Alive
> 
< HTTP/1.1 200 OK
< Date: Sat, 11 Jan 2025 01:07:56 GMT
< Transfer-Encoding: chunked
* Ignoring Transfer-Encoding in CONNECT 200 response
< 
* CONNECT phase completed
* CONNECT tunnel established, response 200
* ALPN: offers h2,http/1.1
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
*  CAfile: /etc/ssl/certs/ca-certificates.crt
*  CApath: /etc/ssl/certs
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS handshake, Finished (20):
* SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384
* ALPN: server accepted h2
* Server certificate:
*  subject: CN=hnrss.org
*  start date: Dec  9 08:18:53 2024 GMT
*  expire date: Mar  9 08:18:52 2025 GMT
*  subjectAltName: host "hnrss.org" matched cert's "hnrss.org"
*  issuer: C=US; O=Let's Encrypt; CN=R10
*  SSL certificate verify ok.
* using HTTP/2
* h2h3 [:method: GET]
* h2h3 [:path: /frontpage]
* h2h3 [:scheme: https]
* h2h3 [:authority: hnrss.org]
* h2h3 [user-agent: curl/7.88.1]
* h2h3 [accept: */*]
* Using Stream ID: 1 (easy handle 0x55de7a757ce0)
> GET /frontpage HTTP/2
> Host: hnrss.org
> user-agent: curl/7.88.1
> accept: */*
> 
< HTTP/2 200 
< server: nginx
< date: Sat, 11 Jan 2025 01:07:56 GMT
< content-type: application/xml; charset=utf-8
< last-modified: Fri, 10 Jan 2025 22:48:13 GMT
< x-algolia-url: https://hn.algolia.com/api/v1/search_by_date?numericFilters=created_at_i%3E%3D1735952657&restrictSearchableAttributes=title&tags=front_page
< expires: Sat, 11 Jan 2025 01:19:17 GMT
< cache-control: max-age=900
< x-cache: HIT
< 
<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>Hacker News: Front Page</title><link>https://news.ycombinator.com/</link><description>Hacker News RSS</description><docs>https://hnrss.org/</docs><generator>hnrss v2.1.1</generator><lastBuildDate>Sat, 11 Jan 2025 01:04:17 +0000</lastBuildDate><atom:link href="https://hnrss.org/frontpage" rel="self" type="application/rss+xml"></atom:link><item><title><![CDATA[Portals and Quake]]></title><description><![CDATA[
<p>Article URL: <a href="https://30fps.net/pages/pvs-portals-and-quake/">https://30fps.net/pages/pvs-portals-and-quake/</a></p>
<p>Comments URL: <a href="https://news.ycombinator.com/item?id=42661185">https://news.ycombinator.com/item?id=42661185</a></p>
<p>Points: 39</p>
<p># Comments: 1</p>
]]></description><pubDate>Fri, 10 Jan 2025 22:48:13 +0000</pubDate><link>https://30fps.net/pages/pvs-portals-and-quake/</link><dc:creator>ibobev</dc:creator><comments>https://news.ycombinator.com/item?id=42661185</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=42661185</guid></item>(more items)</* Connection #0 to host gluetun-9d6e4ac1.download.svc.cluster.local left intact
channel></rss>

To Reproduce

Given the use of k8s, I think it might be a bit hard to reproduce the exact setup. I figured I'd ask here first for general advice to see if I'm missing something stupid or obvious. I'm happy to try to give a reproduction case using gluetun, free vpn servers, and docker compose if it helps (in hopes that the problem isn't related to something else :' ) )

Expected behavior

When using a proxy configured via curl_options, FreshRSS should successfully parse feeds that return 200 status codes with valid RSS content (as demonstrated by the working curl command).

FreshRSS version

1.25.0

System information

• Database version: SQLite
• PHP version: 8.2.26
• Installation type: Docker
• Web server type: Apache
• Device: Laptop
• OS: debian bookworm on 6.1.0-25-amd64 with k3s v1.31.4+k3s1
• Browser: Firefox 133.

Additional context

I hope this is the right place to ask this since I've seen related issues, but I'm happy to move this to a discussion instead.