Remove FMT dependency (#1472)

All occurrences of log() have been replaced with qDebug()

bonus meme: remove a bunch of std::string usages in the pubsub client

Fixes #1467

src/singletons/WindowManager.cpp

@@ -13,7 +13,6 @@
 
 #include "Application.hpp"
 #include "debug/AssertInGuiThread.hpp"
-#include "debug/Log.hpp"
 #include "messages/MessageElement.hpp"
 #include "providers/irc/Irc2.hpp"
 #include "providers/irc/IrcChannel2.hpp"
@@ -264,7 +263,7 @@ Window *WindowManager::windowAt(int index)
     {
         return nullptr;
     }
-    log("getting window at bad index {}", index);
+    qDebug() << "getting window at bad index" << index;
 
     return this->windows_.at(index);
 }
@@ -432,7 +431,7 @@ void WindowManager::initialize(Settings &settings, Paths &paths)
 
 void WindowManager::save()
 {
-    log("[WindowManager] Saving");
+    qDebug() << "[WindowManager] Saving";
     assertInGuiThread();
     QJsonDocument document;