[8.x] Fix assertCookieExpired and assertCookieNotExpired checks for session cookies

[inxilpro]

This PR brings the backwards-compatible bugfixes from #35611 into the 8.x branch.

Currently both assertCookieExpired() and assertCookieNotExpired() do not handle session cookies (where they don't have an expires timestamp, and thus will be removed at the end of the browser session).

For example:

$response = TestResponse::fromBaseResponse(
  (new Response())->withCookie(new Cookie('cookie-name', 'cookie-value'))
);

$response->assertCookieExpired('cookie-name'); // Will pass
$response->assertCookieNotExpired('cookie-name'); // Will fail

I've also pulled in the other backwards-compatible cookie tests into this PR so they exist in the 8.x branch as well.

[inxilpro]

This is triggering the same PHP8 error as #35636 — I'll dig into it a little later if it doesn't resolve on its own.