Fix breakage when 'ALPINE_MIRROR' is not provided

See merge request tt-rss/tt-rss!49

Related to 7f3129d4

Add the 'Sessions' class to the autoloader.

See merge request tt-rss/tt-rss!48

Generated using 'composer dump-autoload --optimize'.

Switch to the non-deprecated form of 'session_set_save_handler'.

See merge request tt-rss/tt-rss!44

Translated using Weblate (Chinese (Traditional))

See merge request tt-rss/tt-rss!46

Currently translated at 77.2% (536 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/pt_PT/

Currently translated at 99.5% (691 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/zh_Hant/

Don't reuse the '$matches' array in 'RSSUtils::decode_srcset()'.

See merge request tt-rss/tt-rss!43

Translated using Weblate (Chinese (Traditional))

See merge request tt-rss/tt-rss!45

Currently translated at 99.5% (691 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/zh_Hant/

As of PHP 8.4 the form with more than 2 arguments is deprecated.

This also does some initial work to make the functions behave closer to what SessionHandlerInterface describes.

* https://php.watch/versions/8.4/session_set_save_handler-alt-signature-deprecated
* https://wiki.php.net/rfc/deprecate_functions_with_overloaded_signatures
* https://www.php.net/manual/en/class.sessionhandlerinterface.php

This causes the size of the array to be incorrectly doubled due to the original regex match items being combined with the custom items (i.e. the ones with just 'url' and 'size' keys).

Also rework 'RSSUtils::encode_srcset()' a bit so it looks similar to 'RSSUtils::decode_srcset()'.

Translated using Weblate (Polish)

See merge request tt-rss/tt-rss!42

Currently translated at 100.0% (694 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/pl/

Translated using Weblate (Turkish)

See merge request tt-rss/tt-rss!41

Currently translated at 80.6% (560 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/tr/

Translated using Weblate (German)

See merge request tt-rss/tt-rss!40

Currently translated at 97.9% (680 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/zh_Hant/

Currently translated at 100.0% (694 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/nl/

Currently translated at 100.0% (694 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/fr/

Currently translated at 99.8% (693 of 694 strings)

Translation: TinyTinyRSS/webui
Translate-URL: https://hosted.weblate.org/projects/tt-rss/webui/de/