Display first available pluralization string if parent key of nested pluralization keys

[mkevinosullivan]

If:

• the keyStyle is not flat (i.e., auto or nested), AND
• the value of the key is an object, AND
• the object's keys contain one or more pluralization keys
  then:
• return the value of the first available pluralization key found in the object to display inline in the editor window

[trishrempel]

Example file structure:

{
  "keyName": {
    "one": "There is {{count}} item",
    "other": "There are {{count}} items"
  }
}

Example usage:

t("keyName", { count: myCountVar}) // i18n-ally displays "There is {{count}} item" instead of "{..}"

[terales]

Merged within #970