[feat] engines: add xprivo - general, news, videos (#6641)

Add support for xprivo.com.  Xprivo has a rate-limit of smth like 20 requests
per day without an API key.  However, if you use a proxy like the IPv6 rotating
proxy [1] you basically get unlimited requests.

[1] https://github.com/vojkovic/http-proxy-ipv6-pool-docker

searx/settings.yml

@@ -3231,6 +3231,28 @@ engines:
       description: "Canadian search engine with its own index"
       results: HTML
 
+  - name: xprivo
+    engine: xprivo
+    shortcut: xpr
+    disabled: true
+    inactive: true
+
+  - name: xprivo news
+    engine: xprivo
+    categories: news
+    xprivo_search_type: news
+    shortcut: xprn
+    disabled: true
+    inactive: true
+
+  - name: xprivo videos
+    engine: xprivo
+    categories: videos
+    xprivo_search_type: videos
+    shortcut: xprv
+    disabled: true
+    inactive: true
+
   - name: zapmeta
     engine: xpath
     shortcut: zpm