Implement class SignalVector

It's a templated wrapper for std::vector with an overloaded `operator=`
which triggers a signal.

src/signalvector.hpp

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <pajlada/signals/signal.hpp>
+
+#include <mutex>
+#include <vector>
+
+namespace chatterino {
+
+template <typename TValue>
+class SignalVector
+{
+public:
+    SignalVector &operator=(std::vector<TValue> &other)
+    {
+        this->data = other;
+
+        this->updated.invoke();
+
+        return *this;
+    }
+
+    operator std::vector<TValue> &()
+    {
+        return this->data;
+    }
+
+    pajlada::Signals::NoArgSignal updated;
+
+private:
+    std::vector<TValue> data;
+};
+
+}  // namespace chatterino