feat(supported-version): validate custom_versions

Previously, @danslo reported that he tried to use `custom_versions` without
setting the kind. This isn't the correct behavior.
I've added a validator to alert him of this.

supported-version/src/kind/validate-kinds.ts

@@ -0,0 +1,12 @@
+import { customVersionsValidator } from "./validations/custom-versions-validator";
+import { isKnownKind } from "./validations/is-known-kind";
+import { KindValidator } from "./validator";
+
+export const validateKind: KindValidator = (kind, custom_versions = null): boolean => {
+    return validators.reduce((acc, el) => el(kind, custom_versions), true);
+}
+
+export const validators: KindValidator[] = [
+    isKnownKind,
+    customVersionsValidator,
+];