fix use of the server list in the installer

add the ability to set several servers

remove dependency on grub-common

don't hardcode installer popup dialog size

fix regular expression (closes: 39050)

fix clocksource (closes: 39050)

fix requires (closes: 38921)

add the ability to select the clock source

Check that supported ntp service is installed (closes: #38168).
datetime-functions: Add numeric TZ to list_zone() output
datetime-functions: Declare variable.

datetime-functions: Unquote timezone string (closes: #35355).
test: Update check-timezone.sh for zone1970.tab file.
datetime-functions: Use zone1970.tab file (closes: #37741).

Run tests when building.
Fix/improve: Protect the installer UI from runtime errors on
Added unit-test to check the "timezone" type.
Fixed (type timezone): allow [_-] symbols and more than one "/".

installer: Fix ntp status detection.
installer: Don't use control directly.
installer: Fix NTP service status in the installed system.

Avoid possible script failure.

Add chrony support to the postinstall script (ALT #36213).

Show localized date and time in installer (ALT #35985).

Avoid touching nonexistent service.