Run SVG benchmark

There is a benchmark in the Qt SVG repository. matthias_rauter suggests that we run it. It would be useful for him to have some results in a dashboard. We only run the core benchmarks at this time.

This was discussed in a weekly meeting. It should not be too difficult to implement the change.

There is also a benefit of doing this. There are benchmarks in multiple repositories. Ideally we should run them too. This change is one step towards this.

The benchmark runner fetches work from a server, called the coordinator. The protocol between the benchmark runner and the coordinator needs to change. The coordinator sends information about merged integrations to the runner, including a branch and a SHA. This also needs to include the name of a module.

It should not be necessary to preserve backwards-compatibility. Staging instances can be used for testing. The production instances can be updated at the same time.