Extract RPC API client into a standalone project

[MaksymZavershynskyi]

Our current restaking tool uses RPC client that was designed to work for testing only. We should extract it into a separate proper RPC client for node.

Following the example, the name on GitHub should be near-api-rs, Crates.io - near-api, Rust use namespace - near_api.

[MaksymZavershynskyi]

As discussed with Near developers it would be nice if we have cleanly extracted RPCUser without pulling too many dependencies from nearcore. Specifically, that would allow us to compile tests that use RPCUser with stable instead of nightly.

[frol]

This issue is quite involving, and required quite some refactoring and restructuring:

• nearcore doesn't return structured errors for most use cases of API #2976 (and all the sub-items)
• refactor(chain): expunge rocksdb from near-jsonrpc-primitives dependency tree #4651

[stale]

This issue has been automatically marked as stale because it has not had recent activity in the last 2 months.
It will be closed in 7 days if no further activity occurs.
Thank you for your contributions.

[miraclx]

Update on this: we've successfully completed the task as defined in the original comment as we do now have the new jsonrpc-client built from the ground up specifically to be approachable by actual users and outside internal testing. It currently exists in its own repo: https://github.com/near/near-jsonrpc-client-rs. And we have it published in its initial stages at https://crates.io/crates/near-jsonrpc-client.

However, the higher-level near-api-rs that should draw closer parallels to the revered near-api-js is still WIP but this would serve as a stepping stone for that endeavor.

[frol]

I feel we can close this issue on nearcore side now, and next quarter we will lay out the plans about near-api-rs