Do not use grpid to find last inserted row in chats table

Instead, use last_insert_rowid() function to find the row.

There is no race condition in using last_insert_rowid(), because
last_insert_rowid() returns row id last inserted in this connection. As
we hold the connection during the whole transaction, it is impossible
that some other thread will execute INSERT statement in parallel.

This commit is part of the effort to get rid of sql::get_rowid hack and
use transactions more for related SQL statements.

src/chat.rs

@@ -1184,33 +1184,31 @@ pub fn create_or_lookup_by_contact_id(
     let contact = Contact::load_from_db(context, contact_id)?;
     let chat_name = contact.get_display_name();
 
-    sql::execute(
-        context,
-        &context.sql,
-        "INSERT INTO chats (type, name, param, blocked, grpid, created_timestamp) VALUES(?, ?, ?, ?, ?, ?)",
+    context
+        .sql
+        .start_stmt("create_or_lookup_by_contact_id transaction");
+    context.sql.with_conn(|conn| {
+        let tx = conn.transaction()?;
+        tx.execute(
+        "INSERT INTO chats (type, name, param, blocked, created_timestamp) VALUES(?, ?, ?, ?, ?)",
         params![
-            100,
+            Chattype::Single,
             chat_name,
             match contact_id {
                 DC_CONTACT_ID_SELF => "K=1".to_string(), // K = Param::Selftalk
                 DC_CONTACT_ID_DEVICE => "D=1".to_string(), // D = Param::Devicetalk
-                _ => "".to_string()
+                _ => "".to_string(),
             },
             create_blocked as u8,
-            contact.get_addr(),
             time(),
         ]
-    )?;
-
-    let row_id = sql::get_rowid(context, &context.sql, "chats", "grpid", contact.get_addr());
-    let chat_id = ChatId::new(row_id);
-
-    sql::execute(
-        context,
-        &context.sql,
-        "INSERT INTO chats_contacts (chat_id, contact_id) VALUES(?, ?)",
-        params![chat_id, contact_id],
-    )?;
+        )?;
+        tx.execute(
+            "INSERT INTO chats_contacts (chat_id, contact_id) VALUES((SELECT last_insert_rowid()), ?)",
+            params![contact_id])?;
+        tx.commit()?;
+        Ok(())
+    })?;
 
     if contact_id == DC_CONTACT_ID_SELF {
         update_saved_messages_icon(context)?;
@@ -1218,7 +1216,7 @@ pub fn create_or_lookup_by_contact_id(
         update_device_icon(context)?;
     }
 
-    Ok((chat_id, create_blocked))
+    lookup_by_contact_id(context, contact_id)
 }
 
 pub fn lookup_by_contact_id(