Add 'multipart_uri_whitelist' INI option to control which URL paths are allowed to submit multipart body

[chopins]

Currently, in PHP, users can upload files to the server under any circumstances, even if the PHP script does not include file upload handling.
This not only unnecessarily increases server bandwidth usage but also introduces the security risk of arbitrary file uploads to the server. like : hitcon-ctf-2018-one-line-php-challenge.
So add multipart_uri_whitelist PHP_INI_PERDIR ini option to Allow file uploads only from whitelisted paths.

[iluuu1994]

Seems more like a webserver responsibility, but I'll let Jakub be the judge of that.

[chopins]

Seems more like a webserver responsibility, but I'll let Jakub be the judge of that.

The issue that PHP automatically saves uploaded files to temporary files should still be addressed.
Additionally, since the server cannot determine whether the php script will handle the file upload, PHP needs to make that determination.