feat: Allowing to overwrite the Download Repository aka Download Mirror
When using hugo-bin within corporate environments it is often required to use a corporate proxy repository like Artifactory to download your dependencies, because access to internet is restricted.
I extended your implementation for switching to the extended version and now it is allowing to set a downloadRepo parameter which will replace the default https://github.com
fixes #112
LGTM now, one last thing: maybe it'd be better if we used uvu's hooks to set/reset npm_config_hugo_bin_build_tag and npm_config_hugo_bin_download_repo? https://github.com/lukeed/uvu/blob/master/docs/api.uvu.md#hooks?
I was also not happy with the node env isolation for the test case, but actually did not spent too much time on it. Good Idea with the test suite. I split the test cases in an own suite and ensured that the env variables are really cleaned before each test run.
I do not know if we should split the test case in 2 Files, but until now I guess thats kind of an overkill.
Could move forward with the pull request?