run list by channel server side (GQL)

[trilopin]

Prepare service and store layer to be able to get all the runs linked to a channeled.

At graphql side we have to decide if we evolve the runs root resolver to accept channelID as criteria (and make optional participantOrFollowerID?) or to create another root resolver.

Current:

	runs (participantOrFollowerID: $userID, teamID: $teamID, sort: "name", statuses: ["InProgress"]){
		id
		name
		isFavorite
		playbookID
		ownerUserID
		participantIDs
		metadata { followers }
	}

func (r *RunRootResolver) Runs(ctx context.Context, args struct {
	TeamID                  string `url:"team_id,omitempty"`
	Sort                    string
	Statuses                []string
	ParticipantOrFollowerID string `url:"participant_or_follower,omitempty"`
}) ([]*RunResolver, error) {
...