Endpoint for sending DAC reveal data in Dal node

The dal node must be able to accept data that will be chunked into DAC pages via a POST endpoint. It will then the Verkle tree root hash

Depends on: #3980 (closed)

See: !6574 (merged) - for computing the Verkle tree root hash See: function handle_split_slot in src/bin_dal_node/RPC_server.ml for an example of how POST requests are handled in the DAL node