[GIT-PULLS] [php-src] PR #22926: ext/session: do not reuse session state a save handler tore down

Pull Request: https://github.com/php/php-src/pull/22926
Author: iliaal

`session_regenerate_id()` runs the userland write or destroy handler, then the close handler, and keeps operating on `PS(id)` afterwards. Any of the three can call `session_destroy()`, and `php_session_destroy()` reaches `php_rshutdown_session_globals()` even when the recursive call was rejected, so PS(id) is released and set to NULL before control returns and `zend_string_release_ex()` dereferences it.

Smallest reproducer is a SessionHandler subclass whose `destroy()` calls session_destroy(), followed by `session_regenerate_id(true)`: SIGSEGV on 8.4, 8.5 and master. The check now sits after every handler has run, so the function warns and returns false with the session left closed. I swept the nine SessionHandler methods against fourteen session functions, 126 combinations with each method calling session_destroy() once. session_regenerate_id() was the only function that crashed, from the write, destroy and close handlers, and nothing in the sweep crashes after this change. The two tests jorgsowa adds in #22687 cover write() and destroy() returning false and still pass here.