RangesUtil: fully-open version range (,) is not detected

`RangesUtil.isVersionRange()` (lines 139-143) misses fully-open ranges:

```java
if (versionConstraint.getRange() != null) {
return !Objects.equals(
versionConstraint.getRange().getLowerBound(),
versionConstraint.getRange().getUpperBound());
}
```

For a completely open range such as `(,)` both bounds are `null`, so `Objects.equals(null, null)` returns `true` and the range is *not* flagged. A fully-open range is the least reproducible dependency specification and is exactly what this goal should report.

Suggested fix: treat `(,)` (both bounds null or one bound null) as a version range.

Start at RangesUtil.isVersionRange(), specifically lines 139-143, and inspect how the lower and upper bounds are compared. Verify behavior for a fully open range such as `(,)`, including cases where either bound is null. Done means fully open and partially open ranges are reported as version ranges without changing the handling of bounded ranges.

Written by the indexing model from the issue text.