R1:59c855276b0b

Provide a "--local" flag to "bin/conduit call" to force in-process execution

Summary:
See PHI1692. Currently, it's hard to get a local profile or "--trace" of some Diffusion API methods, since they always proxy via HTTP -- even if the local node can serve the request.

This always-proxy behavior is intentional (so we always go down the same code path, to limit surprises) but inconvenient when debugging. Allow an operator to connect to a node which can serve a request and issue a `--local` call to force in…