Add basic benchmark (#3038)

* Add basic benchmark

* Add basic documentation for how to run and add tests/benchmarks

* Update benchmark example output

* Add changelog entry

Co-authored-by: zneix <zneix@zneix.eu>

benchmarks/src/main.cpp

@@ -0,0 +1,18 @@
+#include <benchmark/benchmark.h>
+#include <QApplication>
+#include <QtConcurrent>
+
+int main(int argc, char **argv)
+{
+    QApplication app(argc, argv);
+
+    ::benchmark::Initialize(&argc, argv);
+
+    QtConcurrent::run([&app] {
+        ::benchmark::RunSpecifiedBenchmarks();
+
+        app.exit(0);
+    });
+
+    return app.exec();
+}