Fix crash that could occur when closing a split before its display name was updated (#4731)

This fixes a crash that could occur when closing a split before the
display name had a chance to update

The reason I found this was because the LiveController change I made
updated display names more regularly

Additionally, we now make sure to not send duplicate `displayNameUpdated` signals
upon each request for channels with CJK characters in their display name

* Default-initialize the `actualDisplayName` with the user's login name to not send an initial display name update if the display name is the same casing as the login name

src/providers/twitch/TwitchChannel.cpp

@@ -73,7 +73,7 @@ namespace {
 TwitchChannel::TwitchChannel(const QString &name)
     : Channel(name, Channel::Type::Twitch)
     , ChannelChatters(*static_cast<Channel *>(this))
-    , nameOptions{name, name}
+    , nameOptions{name, name, name}
     , subscriptionUrl_("https://www.twitch.tv/subs/" + name)
     , channelUrl_("https://twitch.tv/" + name)
     , popoutPlayerUrl_("https://player.twitch.tv/?parent=twitch.tv&channel=" +
@@ -472,7 +472,7 @@ void TwitchChannel::updateStreamTitle(const QString &title)
 
 void TwitchChannel::updateDisplayName(const QString &displayName)
 {
-    if (displayName == this->getDisplayName())
+    if (displayName == this->nameOptions.actualDisplayName)
     {
         // Display name has not changed
         return;
@@ -480,6 +480,8 @@ void TwitchChannel::updateDisplayName(const QString &displayName)
 
     // Display name has changed
 
+    this->nameOptions.actualDisplayName = displayName;
+
     if (QString::compare(displayName, this->getName(), Qt::CaseInsensitive) ==
         0)
     {