build: drop support for building addons with VS 2013 in v9

[bnoordhuis]

Continuation of #7989 in a way. See #13263, it turns out that upgrades to V8 requires floating patches to keep addons building with VS 2013.

That is not a good position to be in and not tenable long-term, that's why I propose to raise the baseline to VS 2015 in node 9.

[gibfahn]

SGTM, that means we support VS2013 up till 2020 (when Node 8 goes out of support) which seems long enough to me.

cc/ @nodejs/platform-windows

[refack]

Just to be clear we're talking about native addons support?
SGTM since MS is giving both VS2017 and VS2017 buildtools for free, and they are able to "cross compile" for older Windows versions.
Sounds relevant also to my CTRL-SHIFT-TAB tab nodejs/node-gyp#1212 a.k.a node-gyp@4

[tniessen]

SGTM. I am not even sure whether Microsoft still offers support for VS2013, their support policy is a little obscured thanks to the number of service packs.

[richardlau]

This was done by 2062a69 (#14764).