Add Run labels in JSON from tw runs dump

[drpatelh]

We are developing a MultiQC module that is able to scrape the output of tw runs dump in order to aggregate metrics into a single report across runs. It would be useful to be able to get run labels directly from the JSON files that we can add to the report. We can then add these to the report to help with filtering / sorting etc.

See MultiQC/MultiQC#2151 (comment)

[swampie]

@drpatelh resource labels or simple labels or both?

[drpatelh]

Both please 🙏🏽 For simple labels we can decorate the MultiQC report for filtering and for resource labels we can try to set something up that scrapes costs from Cost Explorer automatically per run.

[JaimeSeqLabs]

Closed in #364