Replace/remove momentjs library #516
Description
According to some articles, momentjs is a slow/heavy/hard to debug library, and 2020's web projects should not rely on this library.
Performing a quick search on the project, it seems the momentjs is mainly used to calculate time ranges, before/after verifications, calculate time offset, and format dates. Most of these operations( except formatting) can be done using the native elements.
Please evaluate if we can replace or remove momentjs from the time-tracker-ui's dependencies.