Function composite_verify 

pub async fn composite_verify(
    _cfm: SharedConfium,
    params: Value,
) -> Result<Value, RpcError>

composite_verify({ "message": "<base64>", "composite": {...} })

Returns:

{
  "all_verified": true,
  "per_component": [
    { "index": 0, "algorithm": "Ed25519", "verified": true, "error": null }
  ]
}