Adding if_any and unless_any validation conditions

[bitchef]

Hi,
I ran into a situation where I needed this functionality. Thought it would be a worthy addition to Vex.

A validation is applicable (or unapplicable) by using if and unless options. If given a list of conditions, the validation is applicable if all elements of the list evaluate to true whereas if_any and unless_any are triggered if at least one element of the list evaluates to true.

iex> Vex.Validator.validate?([name: "foo", state: "persisted"], if: [name: "foo", state: "new"])
false
iex> Vex.Validator.validate?([name: "foo", state: "persisted"], if_any: [name: "foo", state: "new"])
true

iex> Vex.Validator.validate?([name: "foo", state: "persisted"], unless: [name: "foo", state: "new"])
true
iex> Vex.Validator.validate?([name: "foo", state: "persisted"], unless_any: [name: "foo", state: "new"])
false

Hope it will be useful 😃