GH-4699 Clean some things up

Add a menu to select between MMC/Modrinth format packs instead of the custom dialog
Treat 404s on requests to the Modrinth API as success, as the API returns a 404 if a hash was not found, and we don't want to retry the download in this case
Improve logging

launcher/net/Download.cpp

@@ -122,6 +122,13 @@ void Download::downloadError(QNetworkReply::NetworkError error)
         qCritical() << "Aborted " << m_url.toString();
         m_status = Job_Aborted;
     }
+    else if(error == QNetworkReply::ContentNotFoundError && (m_options & Option::AllowNotFound))
+    {
+        // The Modrinth API returns a 404 when a hash was not found when performing reverse hash lookup, we don't want to treat this as a failure
+        qDebug() << "Received 404 from " << m_url.toString() << ", continuing...";
+        m_status = Job_Finished;
+        return;
+    }
     else
     {
         if(m_options & Option::AcceptLocalFiles)

launcher/net/Download.h

@@ -32,7 +32,8 @@ public: /* types */
     enum class Option
     {
         NoOptions = 0,
-        AcceptLocalFiles = 1
+        AcceptLocalFiles = 1,
+        AllowNotFound =2
     };
     Q_DECLARE_FLAGS(Options, Option)