Have the URE fully support formula premises wrapped in SetLink

[ngeiswei]

Problem

When a rule formula has a set of unordered premises they can be wrapped in a SetLink. For instance a conjunction rule can be expressed as follows

Bind
  And
    X
    Y
  ExecutionOutput
    GroundedPredicate "conjunction-formula"
    And
      X
      Y
    Set
      X
      Y

Wrapping X and Y in a SetLink allows the URE to not create multiple versions of inference trees with different permutations of X and Y. For instance without SetLink, when unifying this rule with some target And Z W it would create 2 inference trees

Bind
  And
    Z
    W
  ExecutionOutput
    GroundedPredicate "conjunction-formula"
    And
      Z
      W
    Z
    W

and

Bind
  And
    Z
    W
  ExecutionOutput
    GroundedPredicate "conjunction-formula"
    And
      Z
      W
    ;; Z and W have been swapped
    W
    Z

Motivation

Wrapping unordered formula premises in SetLink avoids over-representing semantically equivalent inference trees, which ultimately speeds up reasoning.

Task

Currently the URE only supports wrapping all formula premises in SetLink, but in some case only a subset of premises are unordered. So the task here would be to have the URE support wrapping a subset of formula premises in a SetLink.