poll time widget: Add time widget markdown parser to polls

Time widget markdown parser functionality added to poll question header.
The change is brought about by applying `update_elements` function on
the poll question header.And in `rendered_markdown.js` a parsing
function is added to render the timestamp
Fixes zulip#16821

static/js/poll_widget.js

@@ -4,6 +4,7 @@ const render_widgets_poll_widget = require("../templates/widgets/poll_widget.hbs
 const render_widgets_poll_widget_results = require("../templates/widgets/poll_widget_results.hbs");
 
 const people = require("./people");
+const rendered_markdown = require("./rendered_markdown");
 
 class PollData {
     // This object just holds data for a poll, although it
@@ -207,8 +208,10 @@ exports.activate = function (opts) {
         const waiting = !is_my_poll && !has_question;
         const author_help = is_my_poll && !has_question;
 
+        const content = elem.find(".poll-widget");
         elem.find(".poll-question-header").toggle(!input_mode);
         elem.find(".poll-question-header").text(question);
+        rendered_markdown.update_elements(content);
         elem.find(".poll-edit-question").toggle(can_edit);
         update_edit_controls();
 

static/js/rendered_markdown.js

@@ -166,6 +166,26 @@ export const update_elements = (content) => {
         }
     });
 
+    content.find("h4.poll-question-header").each(function () {
+        if ($(this).text().includes("<time:")) {
+            const text = $(this)
+                .text()
+                .match(/<time:(.*)>/)
+                .pop();
+            const time_string = $(this)
+                .text()
+                .match(/<time:(.*)>/)
+                .pop();
+            const rendered_time = timerender.render_markdown_timestamp(parseISO(time_string), text);
+            $(this).text(
+                $(this)
+                    .text()
+                    .replace(/<time:(.*)>/, ""),
+            );
+            $(this).append(`<time title="${rendered_time.title}">${rendered_time.text}</time>`);
+        }
+    });
+
     content.find("span.timestamp-error").each(function () {
         const time_str = $(this).text().replace("Invalid time format: ", "");
         const text = i18n.t("Invalid time format: __timestamp__", {timestamp: time_str});