Bump Substrate to RC5 (#243)

* Bump Substrate to rc5

* Bump async-std to v1.6.2

There was a bug in v.1.6.0 which kept us locked to v1.5 releases.
I think that's fixed now so I'm bumping this.

* Update bridge node runtime

* Update node service

* Update CLI

* Add SystemWeightInfo type to test runtimes

* Add RPC extension builder to service

* Directly return rpc_extensions_builder

* Allow complex types in service

This comes from Substrate, so I'd rather just keep the code as is

* Update benchmarking code for new CLI