Use case onboarding (#19446)

* Add use case onboarding feature flag
* Add endpoints and storage for whether first admin completed setup
* Add migration for FirstAdminSetupComplete

Co-authored-by: Michael Kochell <6913320+mickmister@users.noreply.github.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

api4/system.go

@@ -68,7 +68,8 @@ func (api *API) InitSystem() {
 	api.BaseRoutes.System.Handle("/notices/{team_id:[A-Za-z0-9]+}", api.APISessionRequired(getProductNotices)).Methods("GET")
 	api.BaseRoutes.System.Handle("/notices/view", api.APISessionRequired(updateViewedProductNotices)).Methods("PUT")
 	api.BaseRoutes.System.Handle("/support_packet", api.APISessionRequired(generateSupportPacket)).Methods("GET")
-	api.BaseRoutes.System.Handle("/onboarding/complete", api.APIHandler(completeOnboarding)).Methods("POST")
+	api.BaseRoutes.System.Handle("/onboarding/complete", api.APISessionRequired(getOnboarding)).Methods("GET")
+	api.BaseRoutes.System.Handle("/onboarding/complete", api.APISessionRequired(completeOnboarding)).Methods("POST")
 }
 
 func generateSupportPacket(c *Context, w http.ResponseWriter, r *http.Request) {
@@ -881,6 +882,29 @@ func updateViewedProductNotices(c *Context, w http.ResponseWriter, r *http.Reque
 	ReturnStatusOK(w)
 }
 
+func getOnboarding(c *Context, w http.ResponseWriter, r *http.Request) {
+	auditRec := c.MakeAuditRecord("getOnboarding", audit.Fail)
+	defer c.LogAuditRec(auditRec)
+	c.LogAudit("attempt")
+
+	if !c.App.SessionHasPermissionTo(*c.AppContext.Session(), model.PermissionManageSystem) {
+		c.SetPermissionError(model.PermissionManageSystem)
+		return
+	}
+
+	firstAdminCompleteSetupObj, err := c.App.GetOnboarding()
+
+	if err != nil {
+		c.Err = model.NewAppError("getOnboarding", "app.system.get_onboarding_request.app_error", nil, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	auditRec.Success()
+	if err := json.NewEncoder(w).Encode(firstAdminCompleteSetupObj); err != nil {
+		mlog.Warn("Error while writing response", mlog.Err(err))
+	}
+}
+
 func completeOnboarding(c *Context, w http.ResponseWriter, r *http.Request) {
 	if !c.App.SessionHasPermissionTo(*c.AppContext.Session(), model.PermissionManageSystem) {
 		c.Err = model.NewAppError("completeOnboarding", "app.system.complete_onboarding_request.no_first_user", nil, "", http.StatusForbidden)