<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
This splits the processor package, so the APIs are in an internal
package, and redefined publicly for logs/metrics/traces.
In preparation for adding profiles to the package.
<!-- Issue number if applicable -->
#### Link to tracking issue
See https://github.com/open-telemetry/opentelemetry-collector/pull/10375
cc @mx-psi
Damien Mathieu