[opamp] Public API package #2046
Description
Currently all the types from the opamp client implementation are within an internal package, this is due to an initial thought of having this client implementation as an incubating module where we could test things internally and add breaking changes if needed, without worrying about affecting users, until we get to a stable API which might be a candidate to extract this implementation elsewhere, similarly to what's done with the opamp-go one.
We've discussed if it could be worth taking the public APIs out of the internal package, even for this incubating module, though it seems like there isn't currently a defined preference on how to proceed, so this issue should help keep track of that discussion and to expand on it in the future, once we have a clearer idea of what we'd like to do with this implementation. More details on this thread.