add thumbnail for image in chatlist item (#4311)

* add thumbnail for image in chatlist item

* added preview for stickers and gifs also

* added last_message_type and last_message_id to ChatListItemFetchResult

addresses link2ext comment

* code optimization

fixes:
https://github.com/deltachat/deltachat-core-rust/pull/4311#discussion_r1162791672

* code formatting

* fix clippy

* add changelog entry

---------

Co-authored-by: meganoahj <s3ccg@testrun.org>
Co-authored-by: Simon Laux <mobile.info@simonlaux.de>

src/summary.rs

@@ -50,6 +50,9 @@ pub struct Summary {
 
     /// Message state.
     pub state: MessageState,
+
+    /// Message preview image path
+    pub thumbnail_path: Option<String>,
 }
 
 impl Summary {
@@ -90,11 +93,22 @@ impl Summary {
             text = stock_str::reply_noun(context).await
         }
 
+        let thumbnail_path = if msg.viewtype == Viewtype::Image
+            || msg.viewtype == Viewtype::Gif
+            || msg.viewtype == Viewtype::Sticker
+        {
+            msg.get_file(context)
+                .and_then(|path| path.to_str().map(|p| p.to_owned()))
+        } else {
+            None
+        };
+
         Self {
             prefix,
             text,
             timestamp: msg.get_timestamp(),
             state: msg.state,
+            thumbnail_path,
         }
     }