WIP: api!: add LIMIT arg to get_chat_media

In Delta Chat desktop we show the 3 recently used WebXDC apps,
which relies on `get_chat_media`, which is quite expensive.
Hopefully adding `LIMIT 3` makes it faster.

Marking this as a breaking change
because it's breaking TypeScript-wise,
but shouldn't be breaking behavior-wise,
because not providing the argument in JSON-RPC
should be equivalent to providing `null`
(which gets converted to `None`).

TODO:
- [ ] Add to CFFI?
- [ ] Docs. Both the core fn and the JSON-RPC.

deltachat-jsonrpc/src/api.rs

@@ -1734,6 +1734,7 @@ impl CommandApi {
         message_type: MessageViewtype,
         or_message_type2: Option<MessageViewtype>,
         or_message_type3: Option<MessageViewtype>,
+        limit: Option<u32>,
     ) -> Result<Vec<u32>> {
         let ctx = self.get_context(account_id).await?;
 
@@ -1745,7 +1746,8 @@ impl CommandApi {
         let or_msg_type2 = or_message_type2.map_or(Viewtype::Unknown, |v| v.into());
         let or_msg_type3 = or_message_type3.map_or(Viewtype::Unknown, |v| v.into());
 
-        let media = get_chat_media(&ctx, chat_id, msg_type, or_msg_type2, or_msg_type3).await?;
+        let media =
+            get_chat_media(&ctx, chat_id, msg_type, or_msg_type2, or_msg_type3, limit).await?;
         Ok(media.iter().map(|msg_id| msg_id.to_u32()).collect())
     }