Fix Compilation Errors When Running Tests with --no-default-features

[varshith257]

Background and Motivation

The --no-default-features flag in our CI pipeline is generating around 800 errors during testing, as some parts of the code rely on std and default features. While the code is expected to be compatible with no_std, the tests are not yet adapted for this.

Steps to Reproduce:

Run tests using the following command:

cargo test --no-default-features --workspace

Observe the 769 errors related to missing imports and methods tied to std and Vec etc...

Tasks to be done:

Task List:

• Review and fix missing std and Vec imports
• Conditionally use alloc for environments where std is not enabled
• Fix errors related to missing methods such as to_string()
• Review test cases for compatibility in no_std mode
• (Optional) Clean up any unused imports related warnings

[Abiji-2020]

@JayWhite2357 any ideas about this issue ??