This fixes the regression where process names weren't appearing for
Darwin probes. Makes testing easier.
Also, changes the process walker to operate on value types. There's no
performance advantage to using reference types for something of this
size, and there appeared to be a data race in the Darwin port that
caused nodes to gain and lose process names over time.
Also, restructures how to enable docker scraping. Default false when run
manually, and enabled via --probe.docker true in the scope script.
- Move peers from flags to args in the app
- Allow users to specify peers as IPs and hostname, both with and without ports
- Allow users to specify peers on ./scope launch, and plumb that through entrypoint.sh and run-app
- Improce ./scope usage text
- Add brief document explaining how to cluster Scope
