Creates a new Arb that generates values from the given block function.

Example for fake generators:

val f = Faker()
forAll(Arb.of(f.address::city)) { c -> c.isNotBlank() }

Example using random class instances:

val f = Faker()
forAll(Arb.of(f.randomClass::randomClassInstance)) { foo: Foo -> foo.bar.s.isNotBlank() }