helper/validation: Add Any() SchemaValidateFunc

`Any()` allows any single passing validation of multiple `SchemaValidateFunc` to pass validation to cover cases where a standard validation function does not cover the functionality or to make error messaging simpler.

Example provider usage:

```go
ValidateFunc: validation.Any(
  validation.IntAtLeast(42),
  validation.IntAtMost(5),
),
```

helper/validation/validation.go

@@ -28,6 +28,24 @@ func All(validators ...schema.SchemaValidateFunc) schema.SchemaValidateFunc {
 	}
 }
 
+// Any returns a SchemaValidateFunc which tests if the provided value
+// passes any of the provided SchemaValidateFunc
+func Any(validators ...schema.SchemaValidateFunc) schema.SchemaValidateFunc {
+	return func(i interface{}, k string) ([]string, []error) {
+		var allErrors []error
+		var allWarnings []string
+		for _, validator := range validators {
+			validatorWarnings, validatorErrors := validator(i, k)
+			if len(validatorWarnings) == 0 && len(validatorErrors) == 0 {
+				return []string{}, []error{}
+			}
+			allWarnings = append(allWarnings, validatorWarnings...)
+			allErrors = append(allErrors, validatorErrors...)
+		}
+		return allWarnings, allErrors
+	}
+}
+
 // IntBetween returns a SchemaValidateFunc which tests if the provided value
 // is of type int and is between min and max (inclusive)
 func IntBetween(min, max int) schema.SchemaValidateFunc {

helper/validation/validation_test.go

@@ -41,6 +41,41 @@ func TestValidationAll(t *testing.T) {
 	})
 }
 
+func TestValidationAny(t *testing.T) {
+	runTestCases(t, []testCase{
+		{
+			val: 43,
+			f: Any(
+				IntAtLeast(42),
+				IntAtMost(5),
+			),
+		},
+		{
+			val: 4,
+			f: Any(
+				IntAtLeast(42),
+				IntAtMost(5),
+			),
+		},
+		{
+			val: 7,
+			f: Any(
+				IntAtLeast(42),
+				IntAtMost(5),
+			),
+			expectedErr: regexp.MustCompile("expected [\\w]+ to be at least \\(42\\), got 7"),
+		},
+		{
+			val: 7,
+			f: Any(
+				IntAtLeast(42),
+				IntAtMost(5),
+			),
+			expectedErr: regexp.MustCompile("expected [\\w]+ to be at most \\(5\\), got 7"),
+		},
+	})
+}
+
 func TestValidationIntBetween(t *testing.T) {
 	runTestCases(t, []testCase{
 		{