TraceCall API

[wgr523]

Proposed changes

add TraceCall in debug API, i.e. debug_traceCall

add backend.StateAtBlock(), RPCGasCap

update gen_config.go by tool gencodec

update web3ext

Types of changes

What types of changes does your code introduce to XDC network? Put an ✅ in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation Update (if none of the other choices apply)
• [ ] Regular KTLO or any of the maintaince work. e.g code style
• [ ] CICD Improvement

Impacted Components

Which part of the codebase this PR will touch base on,

Put an ✅ in the boxes that apply

• [ ] Consensus
• [ ] Account
• [ ] Network
• [x] Geth
• [ ] Smart Contract
• [ ] External components
• [ ] Not sure (Please specify below)

Checklist

Put an ✅ in the boxes once you have confirmed below actions (or provide reasons on not doing so) that

• [x] This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
• [x] Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
• [ ] Tested the backwards compatibility.
• [ ] Tested with XDC nodes running this version co-exist with those running the previous version.
• [ ] Relevant documentation has been updated as part of this PR
• [ ] N/A

Test plan

I already tested with a local xdc node. And we can also do the test on devnet/testnet. Just pick a deployed contract (e.g. XDCValidator) and call its function using debug_traceCall.