Powder snow interior faces should not be culled by non-powder snow blocks

[muzikbike]

The same issue as CaffeineMC/sodium#1163.

The inner faces of powder snow blocks should only be culled by other powder snow blocks. Having the outer faces culled by full solid opaque blocks is a good thing, but having the inner faces also culled by said blocks isn't. For example, it causes the snowy grass block's top texture to become visible, which should never happen.

Vanilla (interior appearance is desirable, but the "exterior" as viewed from Spectator mode underground is not):

MoreCulling 0.17.0 ("exterior" is desirable, interior is not):