ref: Rename relay-spans/span to otel_to_sentry (#4742)

This is in preparation for the spanv2 -> spanv1 and otel -> spanv2
conversions. It also introduces JSON snapshots into tests where
appropriate.

Author: loewenheim

relay-spans/src/lib.rs

@@ -6,9 +6,9 @@
     html_favicon_url = "https://raw.githubusercontent.com/getsentry/relay/master/artwork/relay-icon.png"
 )]
 
-pub use crate::span::otel_to_sentry_span;
+pub use crate::otel_to_sentry::otel_to_sentry_span;
 
 pub use opentelemetry_proto::tonic::trace::v1 as otel_trace;
 
-mod span;
+mod otel_to_sentry;
 mod status_codes;