Support iterating over object children using wildcard

[NassimBtk]

Description

Problem

JFlat's toCSV method can only iterate over JSON arrays to produce CSV rows. When a JSON structure uses an object with dynamic keys (e.g. a map of items keyed by UID, hash, or any arbitrary string), there is no way to expand each child into a separate CSV row.

For example, many REST APIs return collections as objects rather than arrays:

{
  "members": {
    "abc123": { "id": 0, "name": "Drive 0" },
    "def456": { "id": 1, "name": "Drive 1" }
  }
}

Currently, calling toCSV("/members", ...) produces a single row for the members object itself, instead of one row per child entry. The only workaround is to pre-process the JSON externally to convert the object values into an array before passing it to JFlat.

Expected Behavior

JFlat should support a wildcard notation in the entry key path (e.g. /members/*) that expands all direct children of an object into individual CSV rows, just as arrays are automatically expanded today.

This should work with:

• Simple properties: /members/* with properties like id, name
• Nested properties: /members/* with properties like manufacturing/serialNumber, type/default
• Parent references: The existing ../ syntax should continue to work from wildcard-expanded entries

Since * is a valid JSON key, a way to refer to a literal * property (e.g. via escaping) should also be provided to avoid ambiguity.