implement rule evaluation logic

[ploomiz]

---

labels: mergeable

Fixes: #3404

Motivation and Context

This implements evaluation of targeting rules based on the spec in this document:
https://www.notion.so/eppo/Targeting-Rules-64b9b5b25fff42a489c56b11ce0ba95d

Description

This assumes the RAC endpoint will pass an optional array of rules with each experiment config. The assignment function will return null if the targeted attributes passed to the SDK do not match at least one rule.

{
  "experiments": {
    "exp1": {
      "rules": [
        {
          "type": "AND",
          "conditions": [
            {
              "operator": "GTE",
              "attribute": "totalSales",
              "value": 100
            },
            {
              "operator": "LTE",
              "attribute": "totalSales",
              "value": 999
            }
          ]
        }
      ]
    }
  }
}

How has this been tested?

SDK integration and unit tests