[fix] Qwant engines - implement API v3 and add 'quant videos'

The implementation uses the Qwant API (https://api.qwant.com/v3). The API is
undocumented but can be reverse engineered by reading the network log of
https://www.qwant.com/ queries.

This implementation is used by different qwant engines in the settings.yml::

  - name: qwant
    categories: general
    ...
  - name: qwant news
    categories: news
    ...
  - name: qwant images
    categories: images
    ...
  - name: qwant videos
    categories: videos
    ...

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/data/engines_languages.json

@@ -25607,6 +25607,49 @@
     "zh-CN",
     "zh-HK"
   ],
+  "qwant videos": [
+    "bg-BG",
+    "ca-ES",
+    "cs-CZ",
+    "da-DK",
+    "de-AT",
+    "de-CH",
+    "de-DE",
+    "el-GR",
+    "en-AU",
+    "en-CA",
+    "en-GB",
+    "en-IE",
+    "en-IN",
+    "en-MY",
+    "en-NZ",
+    "en-US",
+    "es-AR",
+    "es-CL",
+    "es-ES",
+    "es-MX",
+    "et-EE",
+    "fi-FI",
+    "fr-BE",
+    "fr-CA",
+    "fr-CH",
+    "fr-FR",
+    "hu-HU",
+    "it-CH",
+    "it-IT",
+    "ko-KR",
+    "nb-NO",
+    "nl-BE",
+    "nl-NL",
+    "pl-PL",
+    "pt-BR",
+    "pt-PT",
+    "ro-RO",
+    "sv-SE",
+    "th-TH",
+    "zh-CN",
+    "zh-HK"
+  ],
   "startpage": {
     "af": {
       "alias": "afrikaans"