test: add comprehensive tests for install_npm and install_npm_win functions

- Introduced multiple test cases for the install_npm function, covering basic installation, handling of the no_npm_clean flag, verbose output, special characters in paths, and environment variable inheritance.
- Added tests for the install_npm_win function, ensuring correct URL construction, file removal before installation, and proper handling of different version formats.
- Verified logging and subprocess behavior in various scenarios to ensure robustness of npm installation processes.

Author: ekalinin