Fix: standardize cross-platform path handling in test utilities

[yashksaini-coder]

This issue is to resolve the unfinished implementation and the outdated work of this PR #792

Main objective is to continue where last contributor left off, and go from their to fix the the issue of standardize cross-platform path handling in test utilities
cc: @seetadev @acul71 @pacrob

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Main objective:- Audit and refactor all path manipulations in the core modules and example scripts to use the new cross-platform path utilities provided by libp2p.utils.paths. This includes replacing any OS-specific or hard-coded paths with the standardized functions where applicable, ensuring platform-independent behavior throughout the codebase.

Currently, only test utilities and some testing scripts have adopted the new libp2p.utils.paths utilities. Many core modules and example scripts still use direct path manipulation or OS-specific code, which can lead to errors or inconsistent behavior, especially on non-Linux systems.

[seetadev]

@yashksaini-coder : Great, this looks good. Please add some more details to the issue (example the implementation steps and your roadmap). Get started :)