feat: show reactions in summaries (#5387)

shows the last reaction in chatlist's summaries if there is no
newer message.

the reason to show reactions in the summary, is to make them a _little_
more visible when one is not in the chat. esp. in not-so-chatty or in
one-to-ones chats this becomes handy: imaging a question and someone
"answers" with "thumbs up" ... 

otoh, reactions are still tuned down on purpose: no notifications, chats
are opend as usual, the chatlist is not sorted by reactions and also the
date in the summary refer to the last message - i thought quite a bit
about that, this seems to be good compromise and will raise the fewest
questions. it is somehow clear to the users that reactions are not the
same as a real message. also, it is comparable easy to implement - no
UI changes required :)

all that is very close to what whatsapp is doing (figured that out by
quite some testing ... to cite @adbenitez: if in doubt, we can blame
whatsapp :)

technically, i first wanted to go for the "big solution" and add two
more columns, chat_id and timestamp, however, it seemed a bit bloated if
we really only need the last one. therefore, i just added the last
reaction information to the chat's param, which seems more performant
but also easier to code :)

src/stock_str.rs

@@ -429,6 +429,12 @@ pub enum StockMessage {
         fallback = "⚠️ It seems you are using Delta Chat on multiple devices that cannot decrypt each other's outgoing messages. To fix this, on the older device use \"Settings / Add Second Device\" and follow the instructions."
     ))]
     CantDecryptOutgoingMsgs = 175,
+
+    #[strum(props(fallback = "You reacted %1$s to \"%2$s\""))]
+    MsgYouReacted = 176,
+
+    #[strum(props(fallback = "%1$s reacted %2$s to \"%3$s\""))]
+    MsgReactedBy = 177,
 }
 
 impl StockMessage {
@@ -730,6 +736,27 @@ pub(crate) async fn msg_group_left_local(context: &Context, by_contact: ContactI
     }
 }
 
+/// Stock string: `You reacted %1$s to "%2$s"` or `%1$s reacted %2$s to "%3$s"`.
+pub(crate) async fn msg_reacted(
+    context: &Context,
+    by_contact: ContactId,
+    reaction: &str,
+    summary: &str,
+) -> String {
+    if by_contact == ContactId::SELF {
+        translated(context, StockMessage::MsgYouReacted)
+            .await
+            .replace1(reaction)
+            .replace2(summary)
+    } else {
+        translated(context, StockMessage::MsgReactedBy)
+            .await
+            .replace1(&by_contact.get_stock_name(context).await)
+            .replace2(reaction)
+            .replace3(summary)
+    }
+}
+
 /// Stock string: `GIF`.
 pub(crate) async fn gif(context: &Context) -> String {
     translated(context, StockMessage::Gif).await