Unify rpc

[marioiordanov]

Usage related changes

Users can use http api endpoints via JSON-RPC api.

Development related changes

• Endpoints accessible via HTTP endpoints can be invoked via JSON-RPC
• StarknetRequest -> JsonRpcRequest
• StarknetResponse -> JsonRpcResponse (StarknetResponse, DevnetResponse, Empty)
• Most of the http api methods logic is extracted into <http api endpoint>_impl function which is called from JSON-RPC counterpart
• Updated docs

Checklist:

• Checked out the contribution guidelines
• Applied formatting - ./scripts/format.sh
• No linter errors - ./scripts/clippy_check.sh
• No unused dependencies - ./scripts/check_unused_deps.sh
• No spelling errors - ./scripts/check_spelling.sh
• Performed code self-review
• Rebased to the latest commit of the target branch (or merged it into my branch)
• Updated the docs if needed - ./website/README.md
• Linked the issues resolvable by this PR - linking info
• Updated the tests if needed; all passing - execution info

[FabijanC]

1. Should we eventually document all JSON-RPC methods and parameters in a specification .json file, like Starknet does? We would then not include JSON-RPC examples in these .md documentation files, but would just link to the specification .json.

2. What about testing? My idea is to convert all tests that relied on HTTP methods to rely on JSON-RPC methods. That would be in line with deprecating these HTTP methods and dropping their support in 2-3 months. For integration tests, it would include changing the utility methods to change the sent requests.

[FabijanC]

Regarding the question from my first review:

Should we eventually document all JSON-RPC methods and parameters in a specification .json file, like Starknet does?

I guess for now it stays as it is.

Thanks for addressing the change requests. Approving.

[marioiordanov]

For new JSON-RPC there is an issue created: #508