Add support for protobuf to OTLP exporter

[MikeGoldsmith]

It would be good to update OTLP exporter to support exporting data using protobuf.

This is espcially useful, given that OTLP/HTTP JSON format is experimental where the binary format is stable.

Currently yes but the proto exporter could be fixed to works in browser i believe since it uses protobufjs which works on browser

Originally posted by @vmarchaud in #2322 (comment)

[kolanos]

@MikeGoldsmith Is https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-exporter-collector-grpc not using protobuf with grpc?

[vmarchaud]

@kolanos It is, but it should be possible to use the proto encoding with the HTTP protocol, there already is one for node (https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-exporter-collector-proto) but it would be theorically possible to make it work in the browser (and so merge it with the normal exporter-collector)

[Anusha-Gurajapu]

I would like to pick this up. Please assign this to me.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 14 days.

[dyladan]

We currently support protobuf, json over http, and grpc