* Unify headers already sent errors
Now whenever we need to check where headers were already sent in
ext/session, we call a single location that prints where, keeping it
consistent output wise.
* Unify session aready started errors
Similar to the one for headers.
* Also change session active checks too
This usually go hand in hand with the headers already sent checks, but
is in a separate commit because of the amount of tests it changes.
Using `php_error_docref()` is preferable since it outputs additional
details (which function has been called and whether it is a startup or
shutdown error), uses HTML markup, and also provides a link to the
documentation, if configured.
Since these deprecation warnings have been introduced recently[1][2],
i.e. for PHP 8.4, there are no BC concerns.
[1] <e8ff7c70f9>
[2] <b36eac94d2>
Co-authored-by: Máté Kocsis <kocsismate90@gmail.com>
Several session tests incidentally check the values of INI variables
like session.name and session.save_path. This isn't the point of the
tests, and it can cause spurious failures if (for example) you want to
override your temporary directory while testing. So here, we make the
expected output patterns more lenient.
