[enh] add metasearch engin dogpile.com (XPath)

Add Dogpile engine [1] / merged from [2]

[1] https://www.dogpile.com
[2] https://github.com/searx/searx/pull/2822

searx/settings.yml

@@ -1354,6 +1354,25 @@ engines:
       require_api_key: false
       results: HTML
 
+  - name: dogpile
+    shortcut: dp
+    engine: xpath
+    paging: true
+    page_size: 9
+    # Doesn't work without the 'sc' parameter
+    search_url: https://www.dogpile.com/serp?q={query}&page={pageno}&sc=Gp0GqqlRVflv20
+    url_xpath: //span[@class="web-bing__url"]
+    title_xpath: //a[@class="web-bing__title"]
+    content_xpath: //span[@class="web-bing__description"]
+    categories: general
+    timeout: 3.0
+    disabled: true
+    about:
+      website: https://www.dogpile.com
+      wikidata_id: Q3595363
+      use_official_api: false
+      require_api_key: false
+      results: html
 
 # Doku engine lets you access to any Doku wiki instance:
 # A public one or a privete/corporate one.