[Plugin UT] add more rpcserver UTs

[Jim8y]

Description

This pr adds missing uts for rpcserver

Fixes # (issue)

Type of change

• Optimization (the change is only an optimization)
• Style (the change is only a code style for better maintenance or standard purpose)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Running all UTs.

Test Configuration:

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[Copilot]

Pull Request Overview

This pull request adds comprehensive unit tests for various aspects of the rpcserver functionality including POST request processing, wallet operations, smart contract invocations, node peer handling, blockchain queries, and storage lookup. Key changes include:

• The introduction of new test helper methods and test cases in UT_RpcServer.cs to simulate POST requests.
• Additional unit tests in UT_RpcServer.Wallet.cs, UT_RpcServer.Utilities.cs, UT_RpcServer.SmartContract.cs, UT_RpcServer.Node.cs, and UT_RpcServer.Blockchain.cs covering error cases and edge scenarios.
• Enhancements to verify pagination, invalid input handling, and diagnostic outputs in the blockchain and smart contract tests.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.cs	Adds helper method SimulatePostRequest and tests for malformed JSON and batch requests.
tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.Wallet.cs	Introduces tests covering DumpPrivKey, wallet balance queries, and key import conditions.
tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.Utilities.cs	Adds tests for address validation covering empty strings, wrong length, and invalid checksum scenarios.
tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.SmartContract.cs	Adds tests for various error scenarios in contract invocation and script execution.
tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.Node.cs	Introduces tests for peer status and version information.
tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.Blockchain.cs	Implements tests for block retrieval, mempool state, storage pagination, and transaction queries.

Comments suppressed due to low confidence (1)

tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.SmartContract.cs:282

• The array initializer syntax used inside the new JArray constructor (i.e. '[' and ']') is non‐standard. Consider replacing it with new JArray(item1, item2, …) or using a valid collection initializer for JArray.

var invalidParams = new JArray([

[Wi1l-B0t]

There are many lines that are too long.
Can the be made shorter?

[Jim8y]

There are many lines that are too long. Can the be made shorter?

style can alwayse updated later.