Enable use of Otel baggage via tracing-util crate (hasura#888)

### What

Part of the point of the `tracing-util` crate is to centrally enforce
usage of a single version of opentelemetry libraries.

Previously we added some support for relaying baggage, but not actually
for defining it. This PR exposes the crates and types necessary to add
baggage to the context.

V3_GIT_ORIGIN_REV_ID: 107ec652d4e812f31bbfaa362cedf44b25dc3c39

v3/crates/utils/tracing-util/src/lib.rs

@@ -16,10 +16,12 @@ pub use tracer::{
 
 // re-export things from OpenTelemetry to avoid library users importing their own version and
 // risking mismatches and multiple globals
+pub use opentelemetry::baggage;
 pub use opentelemetry::global::get_text_map_propagator;
 pub use opentelemetry::propagation::text_map_propagator::TextMapPropagator;
 pub use opentelemetry::trace::get_active_span;
 pub use opentelemetry::trace::FutureExt;
 pub use opentelemetry::trace::Status;
 pub use opentelemetry::Context;
+pub use opentelemetry::KeyValue;
 pub use opentelemetry_http::HeaderInjector;

v3/crates/utils/tracing-util/src/setup.rs

@@ -6,7 +6,7 @@ use opentelemetry::{global, trace::TraceError, KeyValue};
 pub use opentelemetry_contrib::trace::propagator::trace_context_response::TraceContextResponsePropagator;
 use opentelemetry_otlp::{WithExportConfig, OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT};
 use opentelemetry_sdk::propagation::{BaggagePropagator, TraceContextPropagator};
-use opentelemetry_sdk::trace::{SpanProcessor, TracerProvider as SDKTracerProvider};
+use opentelemetry_sdk::trace::{SpanProcessor, TracerProvider};
 use opentelemetry_semantic_conventions as semcov;
 
 pub fn initialize_tracing(
@@ -42,7 +42,7 @@ pub fn initialize_tracing(
     .build_span_exporter()?;
 
     let stdout_exporter = opentelemetry_stdout::SpanExporter::default();
-    let tracer_provider = SDKTracerProvider::builder()
+    let tracer_provider = TracerProvider::builder()
         .with_simple_exporter(stdout_exporter)
         .with_batch_exporter(otlp_exporter, opentelemetry_sdk::runtime::Tokio)
         .with_span_processor(BaggageSpanProcessor())