Issue #2631220: Apply changes from MR 2210 to 11.x

Applies the changes from MR 2210 by James Gilliland to 11.x, with some modifications.

Differences from MR 2210:

1. SessionHandler::updateTimestamp() explicitly updates the timestamp. This is consistent with the PHP documentation and with several of Symfony's session storage handlers.
2. Uses the current logic of SessionHandler::read for the new SessionHandler::doRead.
3. Uses the current logic of SessionHandler::write for the new SessionHandler::doWrite.
4. Uses the current logic of SessionHandler::destroy for the new SessionHandler::doDestroy.
5. Adds an ini setting for session.use_strict_mode.
6. Adds #[\SensitiveParameter] to relevant methods.
7. Removes deprecation declaration on WriteSafeSessionHandler::$wrappedSessionHandler.
8. Adds a test.
9. Modifies TestSessionHandlerProxy to implement \SessionUpdateTimestampHandlerInterface. This was required to fix failing tests.

See !2210

Closes #2631220