test: add support for cookie auth and request proxy in jest

[0x62]

Previously all tests were run using password auth, which is fragile and can cause a lot of failures. This patch adds support for using cookie-based auth, as well as HTTPS request proxying while running tests.

The following environment variables should be configured to enable cookie auth and proxy:

TWITTER_COOKIES = [
  "twid=\"u=<ACCOUNT_ID>\"; Expires=XXX; Max-Age=157680000; Domain=twitter.com; Path=/; Secure",
  "auth_token=<ACCESS_TOKEN>; Expires=XXX; Max-Age=157680000; Domain=twitter.com; Path=/; Secure; HttpOnly"
]
PROXY_URL=https://<USERNAME>:<PASSWORD>@us.smartproxy.com:10001

[karashiiro]

Mostly looks good, just a few minor things:

• Merge conflicts 😢
• test-utils.ts should be added to exclude here, I think? Otherwise, it'll be present in the published module when it doesn't need to be. You can verify that it works as expected by just deleting the build output and building again, and checking if there's a test-utils.js in the result (there shouldn't be).
• package-lock.json should be added to the gitignore but that one's on me so don't worry about it, I'll deal with that and set up Corepack after merging.

[0x62]

Should be sorted!