go_modules: replace deprecated ioutil library

[dmitris]

What are you trying to accomplish?

Per golang/go#42026, the io/ioutil package has been deprecated since go1.16. Replace them with the standard invocation of os.MkdirTemp https://pkg.go.dev/os#MkdirTemp.

Anything you want to highlight for special attention from reviewers?

a trivial change in the native helper - Go importresolver

in importresolver/main.go:L32-L34, added the removal of the local file on function exit (to prevent "pollution" of the local filesystem) since TestVCSRemoteForImport returns only the repo.Remote() "portion" of repo and the local directory is not used.

How will you know you've accomplished your goal?

added a unit test go_modules/helpers/importresolver/main_test.go to test the function VCSRemoteForImport (to check for syntax errors etc.)

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.