[web] Remove SubscriptionFormatters, format subscription dates in the frontend (#36409) (#36476)

* Reapply "[web] Remove SubscriptionFormatters, format subscription dates in the…"

This reverts commit 2939e71e5b919529cbb8a602916d5f597d117792.

* Fixup after rename conflict: `nextPaymentDueDate`->`periodEnd`

GitOrigin-RevId: c024a3a2cd08c1f8f9d4c99f9ba6f018d334439e

services/web/test/frontend/features/subscription/util/is-in-free-trial.test.ts

@@ -1,6 +1,5 @@
 import { expect } from 'chai'
 import isInFreeTrial from '../../../../../frontend/js/features/subscription/util/is-in-free-trial'
-import dateformat from 'dateformat'
 
 describe('isInFreeTrial', function () {
   it('returns false when no date sent', function () {
@@ -15,10 +14,6 @@ describe('isInFreeTrial', function () {
   it('returns true when date is in the future', function () {
     const today = new Date()
     const sevenDaysFromToday = new Date().setDate(today.getDate() + 7)
-    const sevenDaysFromTodayFormatted = dateformat(
-      sevenDaysFromToday,
-      'dS mmmm yyyy'
-    )
-    expect(isInFreeTrial(sevenDaysFromTodayFormatted)).to.be.true
+    expect(isInFreeTrial(new Date(sevenDaysFromToday).toISOString())).to.be.true
   })
 })

services/web/test/frontend/features/subscription/util/payment-dates.test.ts

@@ -0,0 +1,31 @@
+import { expect } from 'chai'
+import {
+  formatPaymentDate,
+  formatPaymentDateTime,
+} from '../../../../../frontend/js/features/subscription/util/payment-dates'
+
+describe('payment-dates', function () {
+  describe('formatPaymentDate', function () {
+    it('formats a date in UTC', function () {
+      expect(formatPaymentDate('2025-02-20T12:00:00.000Z')).to.equal(
+        'February 20th, 2025'
+      )
+    })
+    it('returns null for missing dates', function () {
+      expect(formatPaymentDate(null)).to.be.null
+      expect(formatPaymentDate(undefined)).to.be.null
+    })
+  })
+
+  describe('formatPaymentDateTime', function () {
+    it('formats a date and time in UTC', function () {
+      expect(formatPaymentDateTime('2025-02-20T12:00:00.000Z')).to.equal(
+        'February 20th, 2025 12:00 PM UTC'
+      )
+    })
+    it('returns null for missing dates', function () {
+      expect(formatPaymentDateTime(null)).to.be.null
+      expect(formatPaymentDateTime(undefined)).to.be.null
+    })
+  })
+})