Add `labgrid_run_binary#tools` attribute.

Users may need to transfer plain files that have been generated for on the execution platform to the device.

Adding labgrid_run_binary#tools would allow for that to happen.

The tools attribute will need to be added to the list that is used to expand_location on args attribute.

A use case is:

preprocess(
    name = "preprocess",
)

labgrid_run_binary(
    name = "process",
    tools = ["preprocess"],
)

postprocess(
    name = "postprocess",
    srcs = ["preprocess", "process"],
)

Without tools, preprocess has to be passed to srcs which is transitioned to Labgrid platform. This duplicates the preprocess step.

Adding tools allows the user to easily decide which configuration they want to transition to.