Added missed license check for channel banner in patch channel API (#30445)

* Added missed license check for channel banner in patch channel API

* Extractced permission check function

server/channels/api4/channel.go

@@ -377,9 +377,12 @@ func patchChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	if patch.BannerInfo != nil && (originalOldChannel.Type != model.ChannelTypeOpen && originalOldChannel.Type != model.ChannelTypePrivate) {
-		c.Err = model.NewAppError("patchChannel", "api.channel.update_channel.banner_info.channel_type.not_allowed", nil, "", http.StatusBadRequest)
-		return
+	if patch.BannerInfo != nil {
+		if channelBannerAppErr := canEditChannelBanner(c.App.License(), originalOldChannel); channelBannerAppErr != nil {
+			channelBannerAppErr.Where = "patchChannel"
+			c.Err = channelBannerAppErr
+			return
+		}
 	}
 
 	rchannel, appErr := c.App.PatchChannel(c.AppContext, oldChannel, patch, c.AppContext.Session().UserId)
@@ -2439,3 +2442,15 @@ func convertGroupMessageToChannel(c *Context, w http.ResponseWriter, r *http.Req
 		c.Logger.Warn("Error while writing response from convertGroupMessageToChannel", mlog.Err(err))
 	}
 }
+
+func canEditChannelBanner(license *model.License, originalChannel *model.Channel) *model.AppError {
+	if license == nil || !license.IsE20OrEnterprise() {
+		return model.NewAppError("", "license_error.feature_unavailable", nil, "feature is not available for the current license", http.StatusForbidden)
+	}
+
+	if originalChannel.Type != model.ChannelTypeOpen && originalChannel.Type != model.ChannelTypePrivate {
+		return model.NewAppError("", "api.channel.update_channel.banner_info.channel_type.not_allowed", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}