feat: allow updater to extend .user.ini on update

When running nextcloud with a web hoster it might be necessary
to extend .user.ini after each update (e.g. adding memory_limit).
To automate this step, an additional config entry may be provided
in config.php that specifies the lines to be added to .user.ini.

If the config option 'user_ini_additional_lines' exists, the provided
value (string or array of strings) will be added to .user.ini.

Signed-off-by: Mathias Koehrer <koehrer08@koehrer-mail.de>
Signed-off-by: skjnldsv <skjnldsv@protonmail.com>

config/config.sample.php

@@ -2460,6 +2460,14 @@ $CONFIG = [
  */
 'upgrade.cli-upgrade-link' => '',
 
+/**
+ * Additional line(s) (string or array of strings)
+ * that will be added to .user.ini on each update by the updater.
+ *
+ * Defaults to ``''`` (empty string)
+ */
+'user_ini_additional_lines' => '',
+
 /**
  * Customize the server logs documentation link for exception handling.
  */