Replace moment timezone adjustments with date-fns timezone helpers and local Date object

[simiadebowale]

We should be able to replace uses of moment-timezone's .tz() helper in our application code and switch to the date-fns timezone helpers or the local Date object. Those helpers rely on polyfilled timezone data, so this should result in some reduction in bundle size for most users.

Important:

• search of Moment usage in codebase
• Convert all the unit test code, we can do that later.
• Be mindful of the differences between the formatting tokens of moment vs date-fns
• Use your best judgment on how much code surrounding the .tz() usage you're replacing to convert to use date-fns. It's ok to break off complicated pieces of this ticket into smaller ones.

AC:

• [ ] No more imports of moment-timezone in VAOS application code, or a set of tickets created to accomplish this
• [ ] Uses of .tz() are appropriately converted to use date-fns or local Date object helpers, or a set of tickets created to accomplish this

[JunTaoLuo]

Is this a duplicate of https://github.com/department-of-veterans-affairs/va.gov-team/issues/22635?