help forking jsonrpc

We're currently forking jsonrpc for use in our enclave. Thanks @dingelish for your previous upgrades on `serde`.

We're now stuck. If you build
https://github.com/scs/substraTEE-worker/tree/upgrade-deps/enclave
(build it easily in our docker: https://www.substratee.com/howto_worker.html#using-docker)

as-is the build should work, but if you add the dependency of [our fork of jsonrpc-core](https://github.com/scs/jsonrpc/tree/no_std), we get std collisions.

just enable this dependency and the build will fail
https://github.com/scs/substraTEE-worker/blob/60c0c15635d8fff5c21ac376fa4e463857689d6f/enclave/Cargo.toml#L75-L78

Our end goal is to use `jsonrpc-ws-server` where well have to replace transport layer deps with mesalock-forks....

May we kindly ask for your support porting this crate to SGX?

Reproduce the build in the enclave directory from the substraTEE-worker upgrade-deps branch, using the linked Docker instructions. Compare the working build with enclave/Cargo.toml lines 75–78 enabled and investigate the reported std collisions. Done would require a decided, tested path for using the jsonrpc forks and supporting the requested SGX transport dependencies.

Written by the indexing model from the issue text.