Add optional PLIWS

[Sneper-Breeze]

This PR makes Tane and AfdMetricCalc use PLIWS only when explicitly enabled via a boolean flag.

Changes:

• In AfdMetricCalc (src/core/algorithms/fd/afd_metric):

  • Added methods to support computations with both PLI and PLIWS.
  • Rewrote ExecuteInternal logic using std::variant to select between PLI and PLIWS based on the use_pliws flag (default: false).

• In TaneCommon:

  • Rewrote ComputeDependencies logic with std::variant to work with both PLI and PLIWS.

Behavior:

• The public interface remains unchanged for existing callers. An optional use_pliws parameter (default false) can now be passed at algorithm creation.
• Old code continues to work as before.

Testing:

• Added new tests for AfdMetricCalc with and without PLIWS to verify correctness.
• All existing tests still pass, confirming no regression.