feat(app): replace moment.js with native Intl API for date handling

[bhanufyi]

moment-timezone is only used in one place. We could use the native JavaScript APIs to replace its functionality and avoid external dependencies for the most part. Also, using date-fns instead of moment would be more beneficial for future use cases, as it's a lightweight library. I've hardcoded timezones that are returned by the Intl API. Let me know what you think of it (it mostly resembles what other apps provide, so we shouldn't run into any edge cases).

[bhanufyi]

Thanks for the review @kanielv, I have created a constants folders and added those in a file

[kanielv]

Lgtm