Add sibling value tests

[beck]

Problem

When the json is pretty, it looks like:

"properties": {
  "title": "some title",
  "count": 4,
  "visible": false,
  "description": "some long description"
}

And the include keys are easy: ["properties.title", "properties.description"].

When the json is cruel it looks like:

"properties": [
  {"name": "title", "value": "some title"},
  {"name": "count", "value": 4},
  {"name": "description", "value": "some description"},
  {"name": "visible", "value": true}
]

And the include keys are: ["properties.0.value", "properties.3.value"]. This is unacceptably brittle because the array order is now important. If the json is sourced from an a 3rd party (and order can not be enforced, or new props are added) the include key config is broken. It also destroys readability, it is no longer clear why props 0 & 3 require translation.

Solution

Introduce a sibling test, making the key config: ["properties.#.value(name=title|description)"]

The code to support this is a bit dense but the resulting config is fairly simple. The order dependency is removed and config self-documentation is restored.

ping @imorrison

[imorrison]

:+1: