SDK/Export concepts leaked into API.

[cijothomas]

https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry/src/common.rs#L426
https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry/src/logs/mod.rs#L27
The above are part of Public API of the OpenTelemetry-API create. Its about "Export" which is an SDK only concept.
Wondering if this is intentional or accidental? If it is not intentional, we should move them into SDK befoe 1.0 stable.

(There are few other similar issues, will open separate issues to track them)