This improves `sc-service` API by not requiring the whole
`&Configuration`, using specific configuration options instead.
`RpcConfiguration` was also extracted from `Configuration` to group all
RPC options together.

We don't use Substrate's CLI and would rather not use `Configuration`
either, but some key public functions require it even though they
ignored most of the fields anyway.

`RpcConfiguration` is very helpful not just for consolidation of the
fields, but also to finally make RPC optional for our use case, while
Substrate still runs RPC server on localhost even if listening address
is explicitly set to `None`, which is annoying (and I suspect there is a
reason for it, so didn't want to change the default just yet).

While this is a breaking change, most developers will not notice it if
they use higher-level APIs.

Fixes https://github.com/paritytech/polkadot-sdk/issues/2897

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Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>