⚖️🌡️ Weighted Rank-Based Metrics

[mberr]

This PR adds support for individual weights for each ranking tasks, in preparation for adding macro evaluation.

It partially re-implements the changes #812 based upon the changes from #786.

In particular, it adds weighting options to

• arithmetic mean rank
• geometric mean rank
• harmonic mean rank
• median rank
• median absolute deviation
• hits at k

as well as their

• inverses
• expected values
  • AMR
  • GMR
  • IHMR
  • H@k
• variances
  • AMR
  • GMR
  • IHMR
  • H@k
• expectation normalized metrics
• re-indexed metrics
• z-adjusted metrics

Not solved by this PR and postponed to a separate follow-up PR:

• calculating closed form expectation / variance of weighted GMR
• calculating the macro-weights & adding an appropriate evaluator