Merge JTL results from different tasks

[eperez84]

Is your feature request related to a problem? Please describe.
No

Describe the feature you'd like
Would be great if JTLs for tests run using different tasks could be merged automatically. Currently if we want to generate reports using JMeter or another tool, we have to manually merge the files before creating a consolidated report.

Additional context

1. Execute a load test using two or more tasks
2. Wait for test to complete
3. View test artifacts, notice that there's 2 or more JTL files