Extracting email functions into a service (#14802)

* Extracting email functions into a service

* Fixing two shadowing errors

* Address PR review comments

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/team_local.go

@@ -84,7 +84,7 @@ func localInviteUsersToTeam(c *Context, w http.ResponseWriter, r *http.Request)
 		}
 		auditRec.AddMeta("errors", errList)
 		if len(goodEmails) > 0 {
-			c.App.SendInviteEmails(team, "Administrator", "mmctl "+model.NewId(), goodEmails, *c.App.Config().ServiceSettings.SiteURL)
+			c.App.Srv().EmailService.SendInviteEmails(team, "Administrator", "mmctl "+model.NewId(), goodEmails, *c.App.Config().ServiceSettings.SiteURL)
 		}
 		// in graceful mode we return both the successful ones and the failed ones
 		w.Write([]byte(model.EmailInviteWithErrorToJson(invitesWithErrors)))
@@ -101,7 +101,7 @@ func localInviteUsersToTeam(c *Context, w http.ResponseWriter, r *http.Request)
 			c.Err = model.NewAppError("localInviteUsersToTeam", "api.team.invite_members.invalid_email.app_error", map[string]interface{}{"Addresses": s}, "", http.StatusBadRequest)
 			return
 		}
-		c.App.SendInviteEmails(team, "Administrator", "mmctl "+model.NewId(), emailList, *c.App.Config().ServiceSettings.SiteURL)
+		c.App.Srv().EmailService.SendInviteEmails(team, "Administrator", "mmctl "+model.NewId(), emailList, *c.App.Config().ServiceSettings.SiteURL)
 		ReturnStatusOK(w)
 	}
 	auditRec.Success()