Break out helper functions from the frontend's managers and stores (#3920)

* Move destructor call to each manager/store constructor for safety

* Break out utility functions

frontend/src/utility-functions/time.ts

@@ -0,0 +1,14 @@
+export function localizeTimestamp(utc: string): { timestamp: string; year: string } {
+	// Timestamp
+	const date = new Date(utc);
+	if (Number.isNaN(date.getTime())) return { timestamp: utc, year: `${new Date().getFullYear()}` };
+
+	const timezoneName = Intl.DateTimeFormat(undefined, { timeZoneName: "longGeneric" })
+		.formatToParts(new Date())
+		.find((part) => part.type === "timeZoneName");
+
+	const dateString = `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, "0")}-${String(date.getDate()).padStart(2, "0")}`;
+	const timeString = `${String(date.getHours()).padStart(2, "0")}:${String(date.getMinutes()).padStart(2, "0")}`;
+	const timezoneNameString = timezoneName?.value;
+	return { timestamp: `${dateString} ${timeString} ${timezoneNameString}`, year: String(date.getFullYear()) };
+}