Add test for cookie name case not being respected.

[caarmen]

Checklist

This PR adds a test to reproduce the issue reported here:

• Cookie names are converted to lower case, causing cookie assertion failures #879

This PR suggests a test to verify that a cookie assertion will respect the case of the cookie name.

The test:

• Has a server which sets a cookie Alpha=one
• Expects: .expect(cookies.set({ name: 'Alpha', options: ['domain', 'path', 'httponly'] }))
• Fails

Note that the test passes if you put alpha in lower case in the expect.

• I have ensured my pull request is not behind the main or master branch of the original repository.
• I have rebased all commits where necessary so that reviewing this pull request can be done without having to merge it first.
• I have written a commit message that passes commitlint linting.
• I have ensured that my code changes pass linting tests.
• I have ensured that my code changes pass unit tests.
  • Nope, the point is to demonstrate a failing test :)
• I have described my pull request and the reasons for code changes along with context if necessary.