test: add and fix existing ethermint rpc unit test

[skosito]

Description

Rpc folder was moved from ethermint repo to node, but unit tests weren't. This PR moves existing unit tests as well, with some fixes i will provide in comments so PR is easier to review - otherwise there are no significant changes. Modifications for unit tests to address rpc changes will be added in next PR to make review of those changes easier.

Partially closes: #2283

Type of change

Unit tests

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Include instructions and any relevant details so others can reproduce.

• Tested CCTX in localnet
• Tested in development environment
• Go unit tests
• Go integration tests
• Tested via GitHub Actions

Checklist:

• I have added unit tests that prove my fix feature works

[gitguardian]

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🔎 Detected hardcoded secrets in your pull request

GitGuardian id	GitGuardian status	Secret	Commit	Filename
11033145	Triggered	Generic High Entropy Secret	7dd8aa6	cmd/zetae2e/local/accounts.go	View secret
11033146	Triggered	Generic High Entropy Secret	7dd8aa6	cmd/zetae2e/local/accounts.go	View secret

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[lumtis]

Would it makes sense to add rpc/backend in test coverage scope?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.22%. Comparing base (a28d7e1) to head (077eb2e).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2294      +/-   ##
===========================================
- Coverage    69.68%   68.22%   -1.46%     
===========================================
  Files          281      298      +17     
  Lines        16644    18857    +2213     
===========================================
+ Hits         11598    12865    +1267     
- Misses        4570     5355     +785     
- Partials       476      637     +161     

Files	Coverage Δ
rpc/backend/tx_info.go	59.79% <100.00%> (ø)

... and 16 files with indirect coverage changes

[skosito]

Would it makes sense to add rpc/backend in test coverage scope?

added whole rpc folder, and coverage is 57% https://app.codecov.io/gh/zeta-chain/node/tree/rpc-tests/?trend=3%20months

with new issue to add more tests probably will increase, i would like to keep types folder as well since some new tests will touch that code as well

[lumtis]

Would it makes sense to add rpc/backend in test coverage scope?

added whole rpc folder, and coverage is 57% https://app.codecov.io/gh/zeta-chain/node/tree/rpc-tests/?trend=3%20months

with new issue to add more tests probably will increase, i would like to keep types folder as well since some new tests will touch that code as well

Global test coverage only lose 1.5%, this is fine

[lumtis]

LGTM