Introducing OneOf and NoneOf

[detro]

Closes #7
Closes #8
Closes #9

Validators added here, per package:

• int64validator
  • OneOf(int64...), NoneOf(int64...)
• float64validator
  • OneOf(float64...), NoneOf(float64...)
• numbervalidator
  • OneOf(*big.Float...), NoneOf(*big.Float...)
• stringvalidator
  • OneOf(bool, float64...), NoneOf(bool, float64...)
  • NOTE: the extra bool parameter is to enable/disable case sensitivity

The validators are designed to restrict use to the primitive types, and it will throw errors if used against any collection type.

Implementation for all but the stringvalidator package is provided by the primitivevalidator package, that holds the bulk of the logic.

[bendbennett]

Looks good!
Left a comment but I'm not sure it's a significant concern.
I've only reviewed genericvalidator package as you mentioned.

[bendbennett]

LGTM. Couple of minor comments but nothing blocking. Guess the only question I have is around naming of the internal pkg, for instance are we going to use primitivevalidator and collectionvalidator, complexvalidator etc.

[detro]

About the internal/ package naming, I don't know what's best to do. I picked primitivevalidator just because in the FW codebase, the attr.Type implementation for them is of type primitive. And they are "Golang primitives".

For the collections, I don't have a better name 🤷 , so I'd go for something like collection*, or bunchofstuff* 😄

[github-actions]

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