fix(deps): bump https-proxy-agent with bugfixes

[colinrotherham]

This pull request is a follow-up to npm/npm#16868

What does it do?
Updates to node-https-proxy-agent@2.0.0

I've also including a regenerated package-lock.json as the node-https-proxy-agent update removed a package required by nyc, plus a few other changes since 2.4.10

What does it fix?
This fixes missing npm options from npm/npm#16868 (e.g. cafile and strict-ssl) not working when under a proxy. Particularly when self-signed certificates are used.

[colinrotherham]

The AppVeyor test run showed missing locate-path due to lock file changes from:

npm install https-proxy-agent@2.0.0 --save

Instead, I've manually edited package.json and ran npm install again. The package-lock.json changes weren't as drastic this time. The tests run successfully now.