Added url and preview_html params to search API results

Allows easy direct linking and usage of the HTML preview content
we show in the UI when viewing search results.
Note: preview_html content is a rough representation only, it does not
match exactly what was matched in the database-search-operation which
finds the results.

For #3096 and #3080

dev/api/responses/search-all.json

@@ -8,6 +8,11 @@
       "created_at": "2021-11-14T15:57:35.000000Z",
       "updated_at": "2021-11-14T15:57:35.000000Z",
       "type": "chapter",
+      "url": "https://example.com/books/my-book/chapter/a-chapter-for-cats",
+      "preview_html": {
+        "name": "A chapter for <strong>cats</strong>",
+        "content": "...once a bunch of <strong>cats</strong> named tony...behaviour of <strong>cats</strong> is unsuitable"
+      },
       "tags": []
     },
     {
@@ -21,6 +26,11 @@
       "created_at": "2021-05-15T16:28:10.000000Z",
       "updated_at": "2021-11-14T15:56:49.000000Z",
       "type": "page",
+      "url": "https://example.com/books/my-book/page/the-hows-and-whys-of-cats",
+      "preview_html": {
+        "name": "The hows and whys of <strong>cats</strong>",
+        "content": "...people ask why <strong>cats</strong>? but there are...the reason that <strong>cats</strong> are fast are due to..."
+      },
       "tags": [
         {
           "name": "Animal",
@@ -45,6 +55,11 @@
       "created_at": "2020-11-29T21:55:07.000000Z",
       "updated_at": "2021-11-14T16:02:39.000000Z",
       "type": "page",
+      "url": "https://example.com/books/my-book/page/how-advanced-are-cats",
+      "preview_html": {
+        "name": "How advanced are <strong>cats</strong>?",
+        "content": "<strong>cats</strong> are some of the most advanced animals in the world."
+      },
       "tags": []
     }
   ],