Introduce `RpcParams` in sc-cli (#5601)

This PR is a pure refactoring by consolidating all the RPC related
parameters into a dedicated `RpcParams` struct, allowing us at subcoin
to build a custom run cmd without the need to duplicate code.

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Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>