This adds some E2E tests that show how network codes propagate from the
OTLP(/HTTP) exporter to the OTLP receiver (both serving over HTTP and
gRPC). The goal is that as we add the new `consumererror.Error` type and
any related types to the pipeline, we can use these tests to understand
the net effect of the errors.
Most of the tests won't require changes after we add the new error type,
but note the comment in `TestHTTPToHTTP` that shows where the error type
will add functionality.
These tests don't cover a few things right now:
* Any transformation of the errors as they travel back up the pipeline
by internal parts of the the pipeline graph (fanouts, obsreporter,
etc.). These could impact what the OTLP receiver returns, so we may want
to test them later as we touch those components. We may want these
direct tests regardless since these components have a contract with each
other that likely should exist outside our service implementation.
* Retry handling. This hasn't been fully added to the errors yet, so
I'll wait until that's closer to add tests.
Evan Bradley