MM-22706: pass along set_online flag in websocket response (#14591)

* MM-22706: pass along set_online flag in websocket response

To let the client know whether a user has created a post without
being online or not, we get the set_online query param and
pass it down to the websocket event being passed down to the client.

With this PR, the "data" field of the `posted` event will contain
a `set_online` boolean field set to true/false depending on the
query_param set_online value set in the createPost call.

* Setting to false for auto responder

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

app/app_iface.go

@@ -414,8 +414,8 @@ type AppIface interface {
 	CreateOAuthUser(service string, userData io.Reader, teamId string) (*model.User, *model.AppError)
 	CreateOutgoingWebhook(hook *model.OutgoingWebhook) (*model.OutgoingWebhook, *model.AppError)
 	CreatePasswordRecoveryToken(userId, email string) (*model.Token, *model.AppError)
-	CreatePost(post *model.Post, channel *model.Channel, triggerWebhooks bool) (savedPost *model.Post, err *model.AppError)
-	CreatePostAsUser(post *model.Post, currentSessionId string) (*model.Post, *model.AppError)
+	CreatePost(post *model.Post, channel *model.Channel, triggerWebhooks, setOnline bool) (savedPost *model.Post, err *model.AppError)
+	CreatePostAsUser(post *model.Post, currentSessionId string, setOnline bool) (*model.Post, *model.AppError)
 	CreatePostMissingChannel(post *model.Post, triggerWebhooks bool) (*model.Post, *model.AppError)
 	CreateRole(role *model.Role) (*model.Role, *model.AppError)
 	CreateScheme(scheme *model.Scheme) (*model.Scheme, *model.AppError)
@@ -859,7 +859,7 @@ type AppIface interface {
 	SendEmailVerification(user *model.User, newEmail string) *model.AppError
 	SendEphemeralPost(userId string, post *model.Post) *model.Post
 	SendInviteEmails(team *model.Team, senderName string, senderUserId string, invites []string, siteURL string)
-	SendNotifications(post *model.Post, team *model.Team, channel *model.Channel, sender *model.User, parentPostList *model.PostList) ([]string, error)
+	SendNotifications(post *model.Post, team *model.Team, channel *model.Channel, sender *model.User, parentPostList *model.PostList, setOnline bool) ([]string, error)
 	SendPasswordReset(email string, siteURL string) (bool, *model.AppError)
 	SendPasswordResetEmail(email string, token *model.Token, locale, siteURL string) (bool, *model.AppError)
 	SendRemoveExpiredLicenseEmail(email string, locale, siteURL string, licenseId string) *model.AppError