Replace ALWAYS_PARENT with a composite ParentOrElse sampler (#609)
Replace ALWAYS_PARENT with a composite ParentOrElse sampler (#609)

* Split ALWAYS_PARENT based on default behavior if no parent

Signed-off-by: Bogdan Drutu <3f8e17047c2434e5c82a61403e56b9ef3e226d99@gmail.com>

* Rename RootOnly to ParentOrElse

Signed-off-by: Bogdan Drutu <3f8e17047c2434e5c82a61403e56b9ef3e226d99@gmail.com>

* Address feedback

Signed-off-by: Bogdan Drutu <3f8e17047c2434e5c82a61403e56b9ef3e226d99@gmail.com>

* More feedback

Signed-off-by: Bogdan Drutu <3f8e17047c2434e5c82a61403e56b9ef3e226d99@gmail.com>
open-telemetry/opentelemetry-specification,open-telemetry/opentelemetry-specification