MM-53107 Add setting to limit the max number of markdown nodes (#24414)

* MM-53107 Add setting to limit the max number of markdown nodes

* Add extra validation for a couple config fields

* Add new setting to telemetry

webapp/channels/src/components/admin_console/admin_definition.jsx

@@ -3056,6 +3056,15 @@ const AdminDefinition = {
                         key: 'DisplaySettings.CustomURLSchemes',
                         isDisabled: it.not(it.userHasWritePermissionOnResource(RESOURCE_KEYS.SITE.POSTS)),
                     },
+                    {
+                        type: Constants.SettingsTypes.TYPE_NUMBER,
+                        key: 'DisplaySettings.MaxMarkdownNodes',
+                        label: t('admin.customization.maxMarkdownNodesTitle'),
+                        label_default: 'Max Markdown Nodes:',
+                        help_text: t('admin.customization.maxMarkdownNodesDesc'),
+                        help_text_default: 'When rendering Markdown text in the mobile app, controls the maximum number of Markdown elements (eg. emojis, links, table cells, etc) that can be in a single piece of text. If set to 0, a default limit will be used.',
+                        isDisabled: it.not(it.userHasWritePermissionOnResource(RESOURCE_KEYS.SITE.POSTS)),
+                    },
                     {
                         type: Constants.SettingsTypes.TYPE_TEXT,
                         key: 'ServiceSettings.GoogleDeveloperKey',

webapp/channels/src/components/admin_console/schema_admin_settings.jsx

@@ -447,7 +447,7 @@ export default class SchemaAdminSettings extends React.PureComponent {
             inputType = 'textarea';
         }
 
-        let value = this.state[setting.key] || '';
+        let value = this.state[setting.key] ?? '';
         if (setting.dynamic_value) {
             value = setting.dynamic_value(value, this.props.config, this.state, this.props.license);
         }

webapp/channels/src/i18n/en.json

@@ -667,6 +667,8 @@
   "admin.customization.enableSVGsTitle": "Enable SVGs:",
   "admin.customization.iosAppDownloadLinkDesc": "Add a link to download the iOS app. Users who access the site on a mobile web browser will be prompted with a page giving them the option to download the app. Leave this field blank to prevent the page from appearing.",
   "admin.customization.iosAppDownloadLinkTitle": "iOS App Download Link:",
+  "admin.customization.maxMarkdownNodesDesc": "When rendering Markdown text in the mobile app, controls the maximum number of Markdown elements (eg. emojis, links, table cells, etc) that can be in a single piece of text. If set to 0, a default limit will be used.",
+  "admin.customization.maxMarkdownNodesTitle": "Maximum Markdown Nodes:",
   "admin.customization.restrictLinkPreviewsDesc": "Link previews and image link previews will not be shown for the above list of comma-separated domains.",
   "admin.customization.restrictLinkPreviewsExample": "E.g.: \"internal.mycompany.com, images.example.com\"",
   "admin.customization.restrictLinkPreviewsTitle": "Disable website link previews from these domains:",