Allow setting the destination branch/tag/ref so users can test the run
conditions based on the branch/tag/ref.
To simulate a pull request an user can define a ref that matches one of these
regular expressions: `refs/pull/(\d+)/head`, `refs/merge-requests/(\d+)/head`
Export clients and related packages.
The main rule is to not import internal packages from exported packages.
The gateway client and related types are totally decoupled from the gateway
service (not shared types between the client and the server).
Instead the configstore and the runservice client currently share many types
that are now exported (decoupling them will require that a lot of types must be
duplicated and the need of functions to convert between them, this will be done
in future when the APIs will be declared as stable).
