Is your feature request related to a problem?

After updating protobuf schema to 1.2.0 in 1164ab6 we can set the is_remote_parent flag when exporting spans and span links with OTLP.

Describe the solution you'd like

Update OTLP exporter to fill the relevant bits in SpanFlags.

Describe alternatives you've considered

none

Additional context

Proto schema PR: open-telemetry/opentelemetry-proto#484
Go implementation: https://github.com/open-telemetry/opentelemetry-go/pull/5194/files