[feat] engines: add tiger.ch engine

Add support for https://tiger.ch (general, news)

It is disabled and inactive by default because it's just a metasearch engine
like SearXNG is, so it's mostly useful for bypassing rate-limits on other
engines: (it has its own German index, but it's not that great) in theory it
supports different locales, but I was too lazy to implement that (I only need
German and English results anyways, which are returned by default...)

searx/settings.yml

@@ -2078,6 +2078,22 @@ engines:
     shortcut: ts
     disabled: true
 
+  - name: tiger
+    engine: tiger
+    categories: general
+    tiger_category: Websuche
+    shortcut: tig
+    disabled: true
+    inactive: true
+
+  - name: tiger news
+    engine: tiger
+    categories: news
+    tiger_category: News
+    shortcut: tign
+    disabled: true
+    inactive: true
+
   - name: tmdb
     engine: xpath
     paging: true