How specify generated to use "@grpc/grpc-js" instead of "grpc"

[pattrickrice]

The npm package is being deprecated and documentation recommends to switch to

Node.js gRPC Library
This library is now only receiving bug fixes and runtime compatibility updates. In April 2021 it will be deprecated and will no longer receive any updates. https://www.npmjs.com/package/grpc#nodejs-grpc-library

The tool generates a problematic import import * as grpc from "grpc"; which should be switched and the README doesn't document if there's an argument that supports the switch.

[pattrickrice]

Ah, sorry just saw this document https://github.com/agreatfool/grpc_tools_node_protoc_ts/blob/4a6e3f7cc8f892aae4e4b914790a45a1b2070a78/doc/grpcjs_support.md#grpcgrpc-js-support