Reorganize ExecutorTask to better distinguish between the task Spec and
the Status.
Split the task Spec in a sub part called ExecutorTaskSpecData that contains
tasks data that don't have to be saved in etcd because it contains data that can
be very big and can be generated starting from the run and the runconfig.
Defining an option to override the user for a run step is too much fine grained
and, for consistency, will require to do the same also for the other steps
(clone, *workspace etc...).
Remove it since it's probably enough to define it at the task level.
Currently we are using different `When` types for every service and convert
between them. This is a good approach if we want to keep isolated all the
services (like if we were using different repos for every service instead of the
current monorepo).
But currently, since When is identical between all the services, simplify this by
using a common When type.
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).