chore(puth): improve performance when running without GUI attached #66
Description
When running Puth in a CI/CD environment it might experience multiple test runners in parallel using it. The problem is that Puth rescales screencast frames which probably results in high CPU usage. Since there will be no GUI attached, we should only rescale the frames "in time", when needed (e.g. when exporting/saving a failed test).
On a modern server with 10C i could hit 90% usage for the Puth process while running 6 testrunners in parallel. I didn't profile it yet but i suspect it is the rescaling of the image since there "should" be no other impacting work. Encoding of snapshots to msgpack is only done on export and everything else is "just" websocket rx/tx though CDP.