Add more HTTPS tests

[Giotino]

Some tests for the HTTPS options.

These tests simulate a real PKI application.
E.g. https://github.com/Giotino/got/blob/ca8d81314ac93bacd5e0c1da207210adf4e85a4a/test/https.ts#L232-L248

Types are messed up, I'm going to fix them soon, I'm also going to add support for pfx, needed for #1364.

This is a draft, I'm going to add more tests covering more functionalities (e.g. key passphrase or invalid certificates).

create-cert-test-server.ts is like https://github.com/lukechilds/create-test-server, but more specific for our needs.

TODO List

• Add PFX test environment
• Fix types

Checklist

• I have read the documentation.
• I have included a pull request description of my changes.
• I have included some tests.
• If it's a new feature, I have included documentation updates in both the README and the types.

[Giotino]

In order to do more deeper HTTPS tests it has been needed to replace https://github.com/lukechilds/create-test-server for those tests.

The new create-https-test-server is an helper in the got test suite. It's extensible and can easily be adapted to create an HTTPS server with the need of every single tests, this is going to be useful when new HTTPS options are going to be added (e.g. the pfx PR).

This has also enabled me to remove external dependencies for testing the expired certificate and the wrong host (https://github.com/sindresorhus/got/pull/1430/files#diff-ef513147d9bbe98f3dc4e9dc04783109L123-R132).

All that said I think this PR is ready for some review.
@szmarczak @sindresorhus

[szmarczak]

Does the tests pass on Windows?

[Giotino]

Does the tests pass on Windows?

Yes, I'm running it on Windows