Support execution on devices via CLI

We need to create a target that can be used via the CLI to transfer files to a device, run a binary on the device, and transfer files back.

Usage would look like:

bazel run --platform=:my-platform //labgrid/cli  -- --put=`pwd`/my_bin:my_bin --put=`pwd`/data:data --get=out:`pwd`/out -- my_bin --some_arg=data

To do this we will require a new labgrid_binary rule. This will take a given src script and wrap it in //labgrid/executor to provide toolchain resolution and setup environment variables.

Then for our use case in the CLI, we will create a target with //labgrid/run as the src:

labgrid_binary(
    name = "cli",
    src = "//labgrid/run",
)