This adds trace context propagation over the grpc/ttrpc calls to a shim.
It also adds the otlp plugin to the runc shim so that it will send
traces to the configured tracer (which is inherited from containerd's
config).
It doesn't look like this is adding any real overhead to the runc shim's
memory usage, however it does add 2MB to the binary size.
As such this is gated by a build tag `shim_tracing`
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
17d4a1357e