Extension: UI Informs/Informed By

[sammysmallman]

Referencing #14 I'm pulling out the "Informs/Informed By" extension into its own issue for discussion.
There are currently two areas i can think of where it is useful to know if and how one parameter is informing another. In this issue we are looking at how the UI in an application is informed by another. For example, When an application wants to show the available languages a device can be set to it would use this parameter to show LANGUAGE_CAPABILITIES, but when actually setting it uses LANGUAGE.

An example:

"name": "LANGUAGE_CAPABILITIES",
"pid": 160,
...
"extensions": {
  "ui-informing": {
    "name" : "LANGUAGE",
    "pid" : 176
  }
}

"name" : "LANGUAGE",
"pid" : 176,
...
"extensions": {
  "ui-informed": {
    "name" : "LANGUAGE_CAPABILITIES",
    "pid" : 160
  }
}

Both extensions if null in the json would default to "This parameter is not informed by another, or does not inform another."