MM-44221: Add admin console setting to enable/disable App Bar (#20224)

* Revert "[MM-39820] Add AppBarEnabled feature flag (#18967)"

This reverts commit ba1b279c5f.

* Add EnableAppBar admin setting

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

config/client.go

@@ -56,6 +56,7 @@ func GenerateClientConfig(c *model.Config, telemetryID string, license *model.Li
 	props["ExperimentalEnableClickToReply"] = strconv.FormatBool(*c.ExperimentalSettings.EnableClickToReply)
 
 	props["ExperimentalCloudBilling"] = strconv.FormatBool(*c.ExperimentalSettings.CloudBilling)
+	props["EnableAppBar"] = strconv.FormatBool(*c.ExperimentalSettings.EnableAppBar)
 
 	props["ExperimentalEnableAutomaticReplies"] = strconv.FormatBool(*c.TeamSettings.ExperimentalEnableAutomaticReplies)
 	props["ExperimentalTimezone"] = strconv.FormatBool(*c.DisplaySettings.ExperimentalTimezone)