Change: XDG compliance with sudo support

[MordechaiHadad]

Summary

• Fixes [BUG]: On Linux /home/<username> is not necessarily the user home directory #396 [REF] Move directory handling to centralized crate #347 "Error: Couldn't create downloads directory" when running under sudo #342

Moved back to XDG instead of hard coding paths as they are brittle.

Description

Moved to XDG compliance for unix using the previously used dirs crate, and added users crate for a more robust sudo handling.

Type of change

• - 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)
• - Documentation update

Checklist

Checklist tick-boxes

1. Conformity

• - My code follows the style guidelines of this project
• - Code is formatted with cargo fmt
• - No clippy warnings (run cargo clippy --all-targets -- -D warnings)

2. Best-Effort

• - My changes generate no new warnings
• - I have performed a self-review of my own code
• - I have commented my code, particularly in hard-to-understand areas

3. Documentation

• - Any documentation that relates to this PR has been updated
  or will be updated in a PR (Link here: )(if applicable)

4. Tests

• - 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

5. Dependencies

• - Any dependent changes have been merged and published in downstream modules

[MordechaiHadad]

Huh so users crate is no longer maintained rip