Rewrite & optimize LimitedQueue (#3798)

* Use circular buffer for LimitedQueue

* Reduce copying of snapshot

* Small optimizations

* Remove unneeded lock statements

* Add LimitedQueue tests

* Fix includes for limited queue benchmark

* Update CHANGELOG.md

* Use correct boost version iterators

* Use a shared_mutex to clarify reads and writes

* Update `find`/`rfind` to return the result as a boost::optional

* Use `[[nodiscard]]` where applicable

* Update comments

* Add a couple more doc comments

* Replace size with get

get is a safe (locked & checked) version of at

* Use std::vector in LimitedQueueSnapshot

* Update LimitedQueue benchmarks

* Add mutex guard to buffer accessors

We do not know whether T is an atomic type or not
so we can't safely say that we can copy the value
at a certain address of the buffer.

See https://stackoverflow.com/a/2252478

* Update doc comments, add first/last getters

* Make limit_ const

* Omit `else` if the if-case always returns

* Title case category comments

* Remove `at`

* Fix `get` comment

* Privatize/comment/lock property accessors

 - `limit` is now private
 - `space` is now private
 - `full` has been removed
 - `empty` now locks

* Remove `front` function

* Remove `back` method

* Add comment to `first`

* Add comment to `last`

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/common/Channel.cpp

@@ -246,23 +246,20 @@ void Channel::deleteMessage(QString messageID)
         msg->flags.set(MessageFlag::Disabled);
     }
 }
+
 MessagePtr Channel::findMessage(QString messageID)
 {
-    LimitedQueueSnapshot<MessagePtr> snapshot = this->getMessageSnapshot();
-    int snapshotLength = snapshot.size();
+    MessagePtr res;
 
-    int end = std::max(0, snapshotLength - 200);
-
-    for (int i = snapshotLength - 1; i >= end; --i)
+    if (auto msg = this->messages_.rfind([&messageID](const MessagePtr &msg) {
+            return msg->id == messageID;
+        });
+        msg)
     {
-        auto &s = snapshot[i];
-
-        if (s->id == messageID)
-        {
-            return s;
-        }
+        res = *msg;
     }
-    return nullptr;
+
+    return res;
 }
 
 bool Channel::canSendMessage() const