Implement workaround for combined emoji (#3469)

src/providers/twitch/TwitchChannel.hpp

@@ -23,6 +23,22 @@
 
 namespace chatterino {
 
+// This is to make sure that combined emoji go through properly, see
+// https://github.com/Chatterino/chatterino2/issues/3384 and
+// https://mm2pl.github.io/emoji_rfc.pdf for more details
+const QString ZERO_WIDTH_JOINER = QString(QChar(0x200D));
+
+// Here be MSVC: Do NOT replace with "\U" literal, it will fail silently.
+namespace {
+    const QChar ESCAPE_TAG_CHARS[2] = {QChar::highSurrogate(0xE0002),
+                                       QChar::lowSurrogate(0xE0002)};
+}
+const QString ESCAPE_TAG = QString(ESCAPE_TAG_CHARS, 2);
+
+const static QRegularExpression COMBINED_FIXER(
+    QString("(?<!%1)%1").arg(ESCAPE_TAG),
+    QRegularExpression::UseUnicodePropertiesOption);
+
 enum class HighlightState;
 
 struct Emote;