🎉: feat: add UnionEnum type with JSON schema enum usage

[kravetsone]

it('JSON schema', () => {
		expect(t.UnionEnum(['some', 'data'])).toMatchObject({
			type: 'string',
			enum: ['some', 'data']
		})
		expect(t.UnionEnum(['some', 1]).type).toBeUndefined()
		expect(t.UnionEnum([2, 1])).toMatchObject({
			type: 'number',
			enum: [2, 1]
		})
		expect(t.UnionEnum([null])).toMatchObject({
			type: 'null',
			enum: [null]
		})
})

Related - #512

JSON Schem 7 spec - https://json-schema.org/draft/2020-12/json-schema-validation#section-6.1.2
Docs - https://json-schema.org/understanding-json-schema/reference/enum

[BleedingDev]

Great addition, I immediately wanted to use it, but it doesn't allow readonly input. Shall I open PR, @SaltyAom? :)