lichen: Filter timezone options based on locale

[otherJL0]

During the installation process, all timezones from the chrono-tz package are presented for the user to select from.

This changes the default behavior by limiting the presented timezones based on the already selected locale information. The locale information is used to find relevant timezones in the /usr/share/zoneinfo/zone1970.tab table. This also allows the removal of chrono-tz as a dependency.

This also provides a simple escape hatch in case the user wants to select from all timezones independent of their locale.

[jplatte]

It makes sense to me that more likely timezones would be presented to the user higher-up, but filtering sounds like the user won't be able to pick a different timezone at all - is that the case?

[otherJL0]

It makes sense to me that more likely timezones would be presented to the user higher-up, but filtering sounds like the user won't be able to pick a different timezone at all - is that the case?

I originally added an escape hatch to select from all timezones at the end of the filtered list. I've made an update to show the option to see all timezones a the start of the list which I hope is a better user experience.