All the validation must be done inside the configstore since it's the source of
truth.
The gateway could also do some validation to avoid bad requests to the
configstore when needed or when the logic resides outside the configstore (like
project setup or user registration)
RemoteRepositoryConfigType defines how a remote repository is configured and
managed. Currently only "remotesource" is supported.
In future other config types (like a fully manual config) could be supported.
`lts` was choosen to reflect a "long term storage" but currently it's just an
object storage implementation. So use this term and "ost" as its abbreviation
(to not clash with "os").
* client: always parse the json error message field and return its contents
* Use ErrBadRequest and ErrNotFound in every handler and command
* Gateway: by default pass underlying service error (configstore, runservice) to
client keeping the status code and message. In future, if some errors must be
masked, we should change the specific parts that need special handling.
