[FEATURE] Trans-code videos and run-pipelines in one stage (or just same time) instead of two

[mattdawkins]

Need the ability to launch both transcode and (test) pipelines at the same time for overnight / background runs

[subdavis]

Due to #602 this will be impossible.

[mattdawkins]

This doesn't mean they have to actually occur at the same time, just occur at the same time from the user's perspective via 1 button click (they can still occur sequentially in the actual backend)

[waxlamp]

@mattdawkins could we solve this with a new pipeline that simply concatenates the two pipelines in question? That would be a very general solution to this and other problems like it.