Fix reading msvs version on Windows

[jgcook935]

• npm install && npm test passes
• tests are included
• documentation is changed or added
• commit message follows commit guidelines

Description of change

Ever since #2547 went in for version 9 our Windows machines can't properly read msvs_version from the .npmrc. Since names with '_' are now changed to '-' we need to change the opts definition. If there's a different way you'd like to handle this let me know and I can update.

[cclauss]

@StefanStojanovic Your review, please.

Also, what are the currently supported values for MSVS?

Why is this in our tests?

node-gyp/.github/workflows/tests.yml

Lines 46 to 47 in bb76021

	echo 'GYP_MSVS_VERSION=2015' >> $Env:GITHUB_ENV
	echo 'GYP_MSVS_OVERRIDE_PATH=C:\\Dummy' >> $Env:GITHUB_ENV

[StefanStojanovic]

Why is this in our tests?

node-gyp/.github/workflows/tests.yml

Lines 46 to 47 in bb76021

	echo 'GYP_MSVS_VERSION=2015' >> $Env:GITHUB_ENV
	echo 'GYP_MSVS_OVERRIDE_PATH=C:\\Dummy' >> $Env:GITHUB_ENV

I've made a draft PR to test this. From what I see, it is required for Python tests to pass. The same code exists in the visual-studio workflow file, but since Python tests are not run there it can be removed. By the way, the last change on that part of the code was done 3 years ago.

[StefanStojanovic]

The change looks good. @jgcook935 could you rebase to the latest main (will require rewriting your test to mocha) so it can run through CI, please?

[StefanStojanovic]

@jgcook935 I can go ahead and apply the changes I mentioned above and move this forward. Please let me know if you want to do it yourself. Thanks.

[StefanStojanovic]

After rebasing and rewriting the test to mocha everything's good. I'm planning to land this on Friday unless someone objects before that.