Build Windows with MSVC 2019

[aminya]

Description of the change

This uses MSVC 2019 to build Atom on Windows. It does this on the windows-2019 image in Azure. To test the backward compatibility, the built Atom is tested on windows-2016.

Verification

The tests pass. Extra tests are added to test the backward compatibility on older Windows.

Drawbacks

none

Release notes

• build Atom with MSVC 2019 on Windows.
• use windows-2019 in the CI

[aminya]

This needs rebasing

[DeeDeeG]

If we want to use Visual Studio 2019, we will need npm >= 6.10.1.

• npm 6.10.1 is the first npm release to include node-gyp v5
  • https://github.com/npm/cli/blob/e2abf495a29ff137820898461c14885247b6770c/CHANGELOG.md#v6101-2019-07-11
• node-gyp v5 is the first version to support Visual Studio 2019
  • https://github.com/nodejs/node-gyp/blob/master/CHANGELOG.md#v500-2019-06-13

Edit: windows-build-tools@5 installs Visual Studio 2017 and doesn't know how to do VS 2019 yet. So that's a moot point right now.

Edit 2: Here's a test run. master branch + Windows 2019 image + npm 6.14.8 (latest npm).
https://dev.azure.com/DeeDeeG/b/_build/results?buildId=587&view=results

[aminya]

We need to update npm in a separate pull request.

[aminya]

Python version is causing issues in the installation of windows-build-tools.

felixrieseberg/windows-build-tools#223

[DeeDeeG]

What was the error with Python 3? I am trying to debug what happened so I know what to do if this comes up again. But I am not sure what happened.

Edit: Endless install log, right?
https://dev.azure.com/DeeDeeG/b/_build/results?buildId=594&view=logs&j=2985f0af-e798-5fdc-91b8-be9f0a3685c5&t=57ffbcdc-0136-5068-0857-08af536fa868

Not sure what causes that. I saw it outside of CI once. I don't think it's to do with Python versions.

[DeeDeeG]

We can drop the windows-build-tools install and save ~two minutes from preparation! 🎉

https://dev.azure.com/DeeDeeG/b/_build/results?buildId=593&view=logs&j=2985f0af-e798-5fdc-91b8-be9f0a3685c5&t=0a53f124-4db9-5fc3-be81-e293757effc7

Committing here, but you have my permission to just delete the commit if you don't want it.

---

By the way: We should be able to drop the npm update on Windows, and the Python install.

If we update the macOS image to 10.15 macOS Catalina, we can drop npm updates altogether on every OS.

[aminya]

I want to test windows-build-tools first. I know I can use Visual Studio, but the installation of Visual Studio is hard for other users. If we can't build Atom using windows-build-tools ourselves, we should drop it from the documentation.

[DeeDeeG]

For the record: windows-build-tools is a convenience script that downloads Visual Studio from Microsoft and Python from Python.org. It's not expected to be much different than directly installing them yourself. It's nice to test just to be sure, but I would be very much surprised if the Visual Studio/Python you get with windows-build-tools actually behaved differently.