feat: add support for local gRPC coordinator/exporter harness

the code now allows the use of a local harness which will spin up a local exporter and coordinator along with some mock exporter resources and an dummy place to use.

It's purely provided for a simple way to test out some of the remote places functionality, without requiring large portions of additional infrastructure to setup different systems to communicate with.

To test it out run:

bazelisk test //bazel/labgrid/local:test

Fixes #42 (closed)