Make DateUtils test non-timezone dependent (#33343)

This was failing locally because my dev box is set to local time rather
than UTC and so the Date class's special date parsing was interpreting
some of the dates as a different day.

Use Date's methods to build the actual date we want so we're not reliant on
the date objet's parsing - that's not what we're trying to test.

packages/shared-components/src/core/utils/DateUtils.test.ts

@@ -9,6 +9,13 @@ import { describe, it, expect } from "vitest";
 
 import { formatSeconds, formatDateForInput } from "./DateUtils";
 
+function makeDate(year: number, month: number, day: number): Date {
+    const date = new Date(0);
+    date.setFullYear(year, month - 1, day);
+    date.setHours(0, 0, 0, 0);
+    return date;
+}
+
 describe("formatSeconds", () => {
     it("correctly formats time with hours", () => {
         expect(formatSeconds(60 * 60 * 3 + 60 * 31 + 55)).toBe("03:31:55");
@@ -26,10 +33,12 @@ describe("formatSeconds", () => {
 });
 
 describe("formatDateForInput", () => {
-    it.each([["1993-11-01"], ["1066-10-14"], ["0571-04-22"], ["0062-02-05"]])(
-        "should format %s",
-        (dateString: string) => {
-            expect(formatDateForInput(new Date(dateString))).toBe(dateString);
-        },
-    );
+    it.each([
+        ["1993-11-01", makeDate(1993, 11, 1)],
+        ["1066-10-14", makeDate(1066, 10, 14)],
+        ["0571-04-22", makeDate(571, 4, 22)],
+        ["0062-02-05", makeDate(62, 2, 5)],
+    ])("should format %s", (dateString: string, date: Date) => {
+        expect(formatDateForInput(date)).toBe(dateString);
+    });
 });