vuelidate: Add function call signature to ValidationRule (#39206)

* Add function definition to ValidationRule

ValidationRule is a function that takes in parameters and then applies them to the inner validator function. The types are currently missing that allow this behavior. This is most useful when building composed functions out of the built-in validators, like so:

```typescript
export const greaterThanZero: ValidationRule = and(minValue(0), not((value: UserInput) => value == 0))
export const greaterThanOrEqualToZero: ValidationRule = minValue(0)
```

Vuelidate "withParams" reference that returns a ValidationRule function: https://github.com/vuelidate/vuelidate/blob/bb23f01ab4f14a813a25cff8defb7788cd8859ac/src/params.js#L36-L55

* unknown -> any for TS < 3.0

* Fix unrelated noImplictAny for TypeScript@next

types/vuelidate/lib/validators.d.ts

@@ -14,6 +14,7 @@ export interface ValidationParams {
 
 // const ValidationRule
 export interface ValidationRule {
+    (...params: any[]): boolean
     $params(): ValidationParams
     $pending(): boolean
 }

types/vuelidate/vuelidate-tests.ts

@@ -19,9 +19,11 @@ const contains = (param: string): CustomRule =>
 
 const mustBeCool3 = helpers.withParams(
     { type: 'mustBeCool3' },
-    (value) => !helpers.req(value) || value.indexOf('cool') >= 0
+    (value: any) => !helpers.req(value) || value.indexOf('cool') >= 0
 )
 
+const mustBeCool3Result: boolean = mustBeCool3(50)
+
 const mustBeCool4 = helpers.regex('mustBeCool4', /^.*cool.*$/)
 
 const mustBeSame = (reference: string) => helpers.withParams(