Data.write(to:options:) crashes if [.atomic, .withoutOverwriting] are passed together

[weissi]

swift-foundation/Sources/FoundationEssentials/Data/Data.swift

Lines 2445 to 2447 in c0532f8

	if options.contains(.withoutOverwriting) && options.contains(.atomic) {
	fatalError("withoutOverwriting is not supported with atomic")
	}

Severe, source breaking bug here. In 5.10 and below, [.atomic, .withoutOverwriting] worked just fine (possibly not achieving the desired behaviour). We've got to back out this change because

1. It's source breaking (works in 5.10, crashes in 6.0)
2. The docs don't mention that .atomic and .withoutOverwriting are mutually exclusive
3. They shouldn't be mutually exclusive
   3.1. On Linux, the man page for open's example for O_TMPFILE contains how to implement [.atomic, .withoutOverwriting]
   3.2. On systems that lack O_TMPFILE, this can still be approximated with write to .tmp_XXXXXX, then rename tmp file (and remove if that fails). That still prevents half-written files