Support to validate uniqueness of values or keys in Type.Array() and Type.Array(Type.Object())

[regis-underdog]

I have found a couple of patterns popping up in my schemas: needing to validate that a schema has a field, say, name but that the name should be "unique". I also have arrays with values that I would like to validate were full of unique values.

For arrays, something like this:

const C = TypeCompiler.Compile(Type.Array(Type.Unique(Type.String())))

const OK = C.Check(['a','b']) // const OK = true
const FAIL = C.Check(['a','a']) // const FAIL = false

Another possibility since the semantics of my idea seems wrong (you'll see why this gets complicated in the second example):

const C = TypeCompiler.Compile(Type.Array(Type.String(), {uniqueValues: true}))

For Arrays of Objects it gets complicated and I have to constantly write out-of-band validators myself. For example, unique keys of name in the array of objects:

const imageSchema = Type.Object(
  {
    name: Type.String({ pattern: rfc1123Regex.source }),
    image: Type.String(),
  }
)

const TypeCompiler.Compile(Type.Array(Type.Unique(imageSchema, {uniqueValuesByKey: ['name']))

const OK = C.Check([{name: 'a', image: 'b'}, {name: 'c', image: 'd'}] // const OK = true
const FAIL = C.Check([{name: 'a', image: 'b'}, {name: 'a', image: 'd'}] // const FAIL = false

I am not sure how to best express the object-key value being unique in this scenario and hopefully it would be general enough to extend for both of these (and other use cases too) since the first example is just an array of unique objects and the second is an array of unique-ish object key-values.

Note: I understand this would not be compatible with the JSON Schema definitions and might be outside the scope of Typebox core functionality. I do see this pattern crop up frequently and I currently need to write out-of-band validators for uniqueness in lots of different places, so I'm hoping it would be valuable!