feat: adds support to additional properties on material renderer

[lucasoares]

Fixes #2492

This is a draft PR initially generated with Copilot and then reworked manually.

I'm not familiar with the jsonforms codebase and don't have much time right now to dive deeply into it. I did a bit of work on top of what Copilot generated, but I didn’t spend too much time polishing it. The goal was mainly to provide a working version of additionalProperties rendering with the Material renderer.

Everything appears to be working: adding and removing data inside both the object and its arrays. That said, this was mostly an experiment to see if Copilot could handle the issue (I may end up using this version in a fork). For this to be production-ready, it will likely need to be redone properly using this as a reference. Since I have 0 context of jsonforms code, I couldn’t provide more detailed instructions for further development.

Schema example:

"propertiesArrayOfValuesByKey": {
  "type": "object",
  "title": "Array of Values by Key",
  "additionalProperties": {
    "type": "array",
    "items": {
      "type": "string"
    },
    "title": "Item"
  }
}

Rendered form:

All actions are working: you can add and remove data inside both the object and the arrays.

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