This PR:

• Implements precondition described in [mdspan.layout.stride.cons]/4.3.
  • Unfortunately, we cannot check this precondition when one or more extents are equal to 0. For example:

  extents = [3, 0, 3, 0]
  strides = [1, 3, 1, 3]
  pairs = [(1, 3), (3, 0), (1, 3), (3, 0)] // these pairs satisfy our precondition
  after sorting = [(1, 3), (1, 3), (3, 0), (3, 0)] // false positive

  "Sorting" approach (presented in this PR) would fail, even though these values satisfy previously mentioned precondition.
• Fixes incorrect strides in the test code.
• Adds extra death tests.