feat: Resend the last 10 messages to new broadcast member (#8151)

Last 10 messages in a broadcast channel are resent. They are sent and encrypted only to the new member, not to other subscribers.

Close #7678

Based on https://github.com/chatmail/core/pull/7854, with the following
changes:

- Refactor and simplify code, don't reuse the existing `get_chat_msgs()`
function
- Document that Param::Arg4 is also used for resent messages
cc818d9099
- It's unclear how exactly to resend webxdc status updates. After
discussing with @r10s, don't resend webxdc's at all for now.
38d57ebb30
- Don't set fake `msg_id` in resent messages
e7d0687d90
Setting the msg_id to `u32::MAX` is hacky, and may just as well break
    things as it may fix things, because some code may use the msg.id to
    load information from the database, like `get_iroh_topic_for_msg()`.
    From reading the code, I couldn't find any problem with leaving the
    correct `msg_id`, and if there is one, then we should add a function
parameter `is_resending` that is checked in the corresponding places.

Easiest to review file-by-file rather than individual commits, probably.
I'll squash-merge this.

---------

Co-authored-by: iequidoo <dgreshilov@gmail.com>

src/test_utils.rs

@@ -275,16 +275,17 @@ impl TestContextManager {
 
         let chat_id = join_securejoin(&joiner.ctx, qr).await.unwrap();
 
-        loop {
+        for _ in 0..2 {
             let mut something_sent = false;
-            if let Some(sent) = joiner.pop_sent_msg_opt(Duration::ZERO).await {
+            let rev_order = false;
+            if let Some(sent) = joiner.pop_sent_msg_ex(rev_order, Duration::ZERO).await {
                 for inviter in inviters {
                     inviter.recv_msg_opt(&sent).await;
                 }
                 something_sent = true;
             }
             for inviter in inviters {
-                if let Some(sent) = inviter.pop_sent_msg_opt(Duration::ZERO).await {
+                if let Some(sent) = inviter.pop_sent_msg_ex(rev_order, Duration::ZERO).await {
                     joiner.recv_msg_opt(&sent).await;
                     something_sent = true;
                 }
@@ -623,25 +624,35 @@ impl TestContext {
     }
 
     pub async fn pop_sent_msg_opt(&self, timeout: Duration) -> Option<SentMessage<'_>> {
+        let rev_order = true;
+        self.pop_sent_msg_ex(rev_order, timeout).await
+    }
+
+    pub async fn pop_sent_msg_ex(
+        &self,
+        rev_order: bool,
+        timeout: Duration,
+    ) -> Option<SentMessage<'_>> {
         let start = Instant::now();
+        let mut query = "
+SELECT id, msg_id, mime, recipients
+FROM smtp
+ORDER BY id"
+            .to_string();
+        if rev_order {
+            query += " DESC";
+        }
         let (rowid, msg_id, payload, recipients) = loop {
             let row = self
                 .ctx
                 .sql
-                .query_row_optional(
-                    r#"
-                    SELECT id, msg_id, mime, recipients
-                    FROM smtp
-                    ORDER BY id DESC"#,
-                    (),
-                    |row| {
-                        let rowid: i64 = row.get(0)?;
-                        let msg_id: MsgId = row.get(1)?;
-                        let mime: String = row.get(2)?;
-                        let recipients: String = row.get(3)?;
-                        Ok((rowid, msg_id, mime, recipients))
-                    },
-                )
+                .query_row_optional(&query, (), |row| {
+                    let rowid: i64 = row.get(0)?;
+                    let msg_id: MsgId = row.get(1)?;
+                    let mime: String = row.get(2)?;
+                    let recipients: String = row.get(3)?;
+                    Ok((rowid, msg_id, mime, recipients))
+                })
                 .await
                 .expect("query_row_optional failed");
             if let Some(row) = row {