[Validation] Add "Integer" rule

[kiaking]

Add validation rule to validate the given number is integer (no decimals). Vuelidate has this built in validator, but I guess it would be easy to implement our own with Number.isInteger(v).

[cuebit]

What do you mean by no decimals? Number.isInteger will still recognise e.g. 1.0 (but not 1.1, etc) as a valid integer.

Isn't this essentially positiveInteger?

That said, positiveInteger and negativeInteger are identical. Not sure if this was a heuristic choice...

[kiaking]

Ah yeah we had positiveInteger... 🤔

What do you mean by no decimals? Number.isInteger will still recognise e.g. 1.0 (but not 1.1, etc) as a valid integer.

Good point. I think we can accept 1.0. This rule should verify that the value can be treated as integer. In our case, in Go for example.

func main() {
	var n int
	n = 1
	n = 1.0 // This works
	n = 1.1 // This is not

	fmt.Printf("%d", n)
}