`ByteStreamPosition`: some more touchups#711

Merged

LebedevRI merged 8 commits intodarktable-org:developfrom LebedevRI:bs-pos

Apr 13, 2024

+342-63

Commits on Apr 12, 2024

BitVacuumerTest: don't use skipManyBits, actually get those bits
LebedevRI
committed
BitStreamer::fill(): produced fill level is sufficient
LebedevRI
committed