unit: also prioritize input devices when triggering devices

unit: also prioritize input devices when triggering devices

As in most cases, tty device without input devices is meaningless.

This also swaps the priority of tty and net:
- input devices are often connected under USB bus, hence may take
  slightly much time to be initialized. As, described in the above,
  in most cases it is allowed that tty devices are initialized just
  before input devices,
- network configuration usually requires much time, e.g. DHCP or RA,
  hence it is better that network interfaces initialized. Then,
  network services can start DHCP client or friends earlier.

Fixes #24026.