feat(run): encapsulate logic to run binary within Labgrid

This simplifies the rules_labgrid API and makes it more high-level by introducing the labgrid_run macro, which hides away some complexity of using labgrid_genrule directly. As a consequence, this also makes the E2E tests more readable.

Currently, this will only work with the DockeStrategy in Labgrid. Work to make it support other strategies will come in a future MR.