Better asserts for github actions for jobs

[plengauer]

we should assert that all are of the same trace, and all have a parent that exists except one, ...

[plengauer]

In the exporter global test, write the content of every single received request to a big file per signal (one for traces, one for logs, one for metrics). Add conditional steps, that if a certain signal is exported, and not using protobuf but json, add additional checks which exit with non zero exit code if failed. These checks are signal specific. For traces, check whether there is one span that has github.actions.type set to job as traceparent, one with the attribute set to step. None should have empty parents. For logs check that there is one that has a span and trace id set. For metrics, simply check that there are job and step and action metrics. Check the job level instrumentations to learn what metrics to expect.