system/essential/verbatim-files: ditch ntp.conf for we'll use systemd-timesyncd from now on.
system/essential/verbatim-files: add systemd/timesyncd.conf.
system/essential/verbatim-files: sysctl.d/99-sysctl.conf: update various tunables.
system/essential/verbatim-files: systemd/logind.conf: handle suspend and hibernate keys.