Get link for merged launches

[owens-ben]

I've been struggling with this all day trying to patch this on my own but I believe this might need changes beyond just the agent and client.

When I run client.mergeLaunches(), there is no way for me to get the link or even the ID of that new launch. This is really frustrating and basically defeats the purpose of tracking the links at all.

It would be great if mergeLaunches could return the link, id, or both.

Edit:
I previously had an implementation which leveraged the ReRun functionality. I would use startLaunch, note the id, run tests in ReRun mode, then finish the tests. This worked well and I had to revert to it in the meantime.