generate blocks rpc commands
I was not able to find the rpc command generate_blocks
see https://github.com/monero-project/monero/blob/9a124f681119855949f6406ecd69c2ad91da9770/utils/python-rpc/framework/daemon.py#L213-L226

I think I can hack it using the `raw_jsonrpc_request` method but would you accept a PR that adds it ?