[mod] typification of SearXNG: add new result type Paper

This patch adds a new result type: Paper

- Python class:   searx/result_types/paper.py
- Jinja template: searx/templates/simple/result_templates/paper.html
- CSS (less)      client/simple/src/less/result_types/paper.less

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

client/simple/src/less/style.less

@@ -309,11 +309,11 @@ article[data-vim-selected].category-social {
   }
 }
 
-.result-paper,
 .result-packages {
   .attributes {
     display: table;
     border-spacing: 0.125rem;
+    margin-top: 0.3rem;
 
     div {
       display: table-row;
@@ -353,12 +353,6 @@ article[data-vim-selected].category-social {
   }
 }
 
-.result-packages {
-  .attributes {
-    margin-top: 0.3rem;
-  }
-}
-
 .template_group_images {
   display: flex;
   flex-wrap: wrap;
@@ -1118,7 +1112,6 @@ summary.title {
     display: none;
   }
 
-  .result-paper,
   .result-packages {
     .attributes {
       display: block;
@@ -1164,3 +1157,4 @@ pre code {
 
 // import layouts of the Result types
 @import "result_types/keyvalue.less";
+@import "result_types/paper.less";