Intercept getters (and setters) in Groovy closures

[asodja]

Groovy creates a different signature for getters in closures, e.g.:

tasks.register("myCheckstyle", Checkstyle) {
      maxErrors = 2
      int currentMaxErrors = maxErrors // <- getter call here
      assert currentMaxErrors == 2
}

We currently don't intercept that. Lets improve our logic and fix that.

[h0tk3y]

Progress in #24949

[h0tk3y]

Done in #24949.