Add gradle/actions/wrapper-validation as a replacement for gradle/wrapper-validation-action

[bigdaz]

Having a single repository to host all of the Gradle GitHub Actions will provide numerous benefits:

1. Easier to stay on top of dependency updates
2. More frequent release cycle
3. Enable integration between different actions like automatic wrapper validation with setup-gradle.

We'll need to retain the existing gradle/wrapper-validation-action for a deprecation cycle: it can simply delegate to gradle/actions/wrapper-validation (similar to gradle/gradle-build-action delegating to gradle/actions/setup-gradle).

Related gradle/wrapper-validation-action#198

[bigdaz]

Implemented in #159