Adds Requirement Type All and Any to FeatureFlags

[Ross Grambo (rossgrambo)]

In response to issue #28.
And as a rewrite of PR #192.

Add Requirement Type All and Any to FeatureFlags

Filters on Feature Flags have always used "Any" logic. Our execution goes through each filter and when a single one returns "true", we end execution and return true. This PR adds "All" logic. For "All", the execution instead goes through each filter and when a single one returns "false", we end execution, returning false. Otherwise we return true.

In short- this PR:

• Moves RequirementType from AspNetCore to the main .Net library.
• Defaults all unspecified Feature Flags to use "Any" logic
• Adds "All" logic to Feature Flag evaluation

Example

"AllFilterFeature": {
  "RequirementType": "All",
  "EnabledFor": [
    {
      "Name": "Targeting",
      "Parameters": {
        "Audience": {
          "Users": [
            "Jeff",
            "Alicia"
          ]
        }
      }
    },
    {
      "Name": "TimeWindow",
      "Parameters": {
        "Start": "Wed, 1 April 2023 00:00:00 GMT",
        "End": "Wed, 30 April 2023 23:59:59 GMT"
      }
    }
  ]

Evaluation

// Called before TimeWindow:
.IsEnabledAsync(AllFilterFeature, new TargetingContext { UserId = "Jeff" }}) // returns false
.IsEnabledAsync(AllFilterFeature, new TargetingContext { UserId = "Anne" }}) // returns false

// Called during TimeWindow:
.IsEnabledAsync(AllFilterFeature, new TargetingContext { UserId = "Jeff" }}) // returns true
.IsEnabledAsync(AllFilterFeature, new TargetingContext { UserId = "Anne" }}) // returns false

[Ross Grambo (rossgrambo)]

I addressed the comments, but I also re-wrote my changes to the FeatureManager to have less edge-cases.

Both Any and And now have the same default: false
Which allows me to remove the edge case for an empty list of filters with a default of true.
The default changes to "true" when the first filter returns true. In the Any case, we stop and return. In the All case, we now have a true default and we continue.

I also combined some of the inner logic so the Contextual and non-Contextual filters have less duplicated code.