fix: required_without() premature return inside foreach loop

[gr8man]

Bug

In Rules::required_without(), the foreach loop over $otherFields
contained early return statements in the dot-path branch (lines 435, 440).
This caused only the first field in a comma-separated list to be evaluated;
all subsequent fields were silently ignored.

For example, required_without[a.*.b, a.*.c] would only check a.*.b
and return immediately, never inspecting a.*.c.

Fix

• Refactored the foreach body so no iteration contains a return statement.
  Each field is independently evaluated, and false is returned only when
  a missing dependency is found.
• Added ?? null coalescing for $fieldSplitArray[1] with a validation
  guard against malformed dot-path fields.
• Added explicit is_array() check before array-key access on the result
  of dot_array_search(), preventing a PHP Warning when it returns null.

Tests

• testRequireWithoutWithMultipleAsterisk – verifies that both a.*.b and
  a.*.d are checked when using required_without[a.*.b, a.*.d].
• testRequireWithoutWithMultipleAsteriskLastMissing – verifies that
  validation fails when the last dot-path field is absent.