Endpoint POST /memory/recall with metadata

[pieroit]

Endpoint GET /memory/recall should remain and log a warning that is going to be deprecated in v2.

The new POST /memory/recall should accept a json with this format:

{
    "text": "...",
    "k": 34,
    "metadata": {}
}

metadata for the moment (as in other endpoints) is a simple flat dictionary to search in AND

In the future we may allow another field vector_db_filter to be sent directly to Qdrant, with Qdrant filter syntax

[valentimarco]

Same as #898, closing the old one to favor this