Refactor Date Functions to use date-fns /date-fns-tz

[christianhelp]

Currently, a lot of the date comparison logic inside of the event section is being done by functions we create instead of using the built-in libraries. Could lead to issue later on if not fixed.

[linear]

CK-114 Refactor Date Functions to use date-fns /date-fns-tz

Currently, a lot of the date comparison logic inside of the event section is being done by functions we create instead of using the built-in libraries. Could lead to issue later on if not fixed.

[christianhelp]

Adding to this, might be worth it to bump date-fns to the most recent version (v4) which actually adds native support for the tz functions