Replace moment/moment-timezone

**Is your feature request related to a problem? Please describe.**
Moment isn't really supported anymore (https://momentjs.com/docs/#/-project-status/) it references sources that cite momentjs as being:

- slow
- heavy (large package)

**Describe the solution you'd like**
Use [dayjs](https://github.com/iamkun/dayjs)

**Describe alternatives you've considered**

- luxon
- date-fns
- js-joda

Start by locating every use of moment and moment-timezone in the CyberChef project and identify the date and timezone behavior each use requires. Evaluate the proposed dayjs replacement against those uses, then verify that the project no longer depends on the old packages and that existing date-related behavior is preserved.

Written by the indexing model from the issue text.