chore: move some Channel signals to TwitchChannel (#6787)

Reviewed-by: pajlada <rasmus.karlsson@pajlada.com>

src/common/Channel.cpp

@@ -37,7 +37,6 @@ Channel::~Channel()
     {
         app->getChatLogger()->closeChannel(this->name_, this->platform_);
     }
-    this->destroyed.invoke();
 }
 
 Channel::Type Channel::getType() const

src/common/Channel.hpp

@@ -61,11 +61,6 @@ public:
     ~Channel() override;
 
     // SIGNALS
-    pajlada::Signals::Signal<const QString &, const QString &, bool &>
-        sendMessageSignal;
-    pajlada::Signals::Signal<const QString &, const QString &, const QString &,
-                             bool &>
-        sendReplySignal;
     pajlada::Signals::Signal<MessagePtr &, std::optional<MessageFlags>>
         messageAppended;
     pajlada::Signals::Signal<std::vector<MessagePtr> &> messagesAddedAtStart;
@@ -74,7 +69,6 @@ public:
         messageReplaced;
     /// Invoked when some number of messages were filled in using time received
     pajlada::Signals::Signal<const std::vector<MessagePtr> &> filledInMessages;
-    pajlada::Signals::NoArgSignal destroyed;
     pajlada::Signals::NoArgSignal displayNameChanged;
     pajlada::Signals::NoArgSignal messagesCleared;