Is there a minimum level of lighting required for a runway to have an instrument approach?
I have no idea about ICAO but as far as I can tell from the FAA's TERPS, there's no general requirement to have any runway or approach lighting at all (see below for an example), although some specific approach types (like CAT II/III ILS) do require it. Where there is lighting, it's used to reduce the visibility minimums, but the calculations assume no approach lighting by default.

This is from 3-1-2(c) (emphasis mine):


  Approach lighting systems extend visual cues to the approaching pilot
  and make the runway environment apparent with less visibility than
  when such lighting is not available. For this reason, lower
  straight-in (not applicable to circling) visibility minimums may be
  established when standard or equivalent approach lighting systems are
  present.


The TERPS concept seems to be that the approach minimums can be reduced depending on the lighting type available. Section 3-3-2 has an example of calculating visibility minimums when there are no approach lights available.

As for a specific example, MDO/PAMD (Middleton Island, AK) has three approaches (2 RNAV (GPS), 1 VOR) but - as far as I can tell - no lighting of any kind. The chart supplement says:


  Rwy 02–20 marked with rwy cones. Rwy 13–31 marked with cones and OTS
  lgts. Many missing.


As you might expect, the approaches are not authorized at night :-)

Finally, part 121/135 passenger flights can't land at night unless the runway is lit (121.590, 135.229), so any airport that handles those flights will have runway lighting at least, and almost certainly approach lighting too.