Difference between internal and external selects: translations and media

From https://forum.getodk.org/t/retrieving-dynamic-media-from-entity/47820

> In the [ODK Question Types documentation](https://docs.getodk.org/form-question-types/#select-from-external-dataset) it says "Selects from external datasets can be used in all the same ways as internal selects". However, in the [Entities documentation](https://docs.getodk.org/entities-intro/#what-s-the-difference-between-entities-and-choice-lists) it states, "Another difference is that there currently isn't support for media or translations in Entity Lists."

Compare the Select from external dataset section in ODK Question Types with the Entities documentation section on the difference between entities and choice lists. Verify the current behavior for translations and media, then update the conflicting statements so both pages accurately describe the distinction and link context consistently.

Written by the indexing model from the issue text.