refactor/improve-rpc-encode-decode

[Janislav]

Pull Request

Closes: PRO-1157

Checklist

Please conduct a thorough self-review before opening the PR.

• I am confident that the code works.
• I have updated documentation where appropriate.

Summary

• Primarily removes any usage of NumberOrHex from the return types of the LP-API -> Should be not breaking because in any case LPs have to handle decoding the result as a hex string already.
• Removes also all usage for NumberOrHex and any WrappedType that is using it in a V2 version of the API.
• Provides a backwards compatible API to avoid breaking the LPs

Non-Breaking changes

In theory, that should be non-breaking. It still needs some more further checking to ensure that, though. We assume that because NumberOrHex can theoretically decode to a hex string, so LPs also have to handle that case already, which means replacing that with a type that always returns as hex should be none-breaking. Apart from that, during the transition over the next version, we keep the old API as it is and give LPs time to change their implementation. With an upcoming version, we will remove this old API.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 32 lines in your changes are missing coverage. Please review.

Project coverage is 72%. Comparing base (5b503b9) to head (27bde52).

Files	Patch %	Lines
state-chain/custom-rpc/src/lib.rs	0%	22 Missing ⚠️
utilities/src/with_std.rs	0%	10 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##            main   #4737    +/-   ##
======================================
- Coverage     72%     72%    -0%     
======================================
  Files        412     412            
  Lines      70705   70580   -125     
  Branches   70705   70580   -125     
======================================
- Hits       51140   50931   -209     
- Misses     17071   17146    +75     
- Partials    2494    2503     +9     

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[msgmaxim]

Not sure if this is important to you PR or not, but just FYI, there is a custom implementation for BoostPoolDepth that uses NumberOrHex as a way to serialize the amounts as hex: https://github.com/chainflip-io/chainflip-backend/blob/5b074d547d261097468df780a7e998754d966e7f/state-chain/runtime/src/runtime_apis.rs#L76C78-L77C1. Shouldn't really matter since the result will be the same, but for consistency you might want to change that to use U256 too.

[Janislav]

As discussed, putting this here into draft for now @AlastairHolmes.