Review the need for filter_sideload_move_temp_file_to_s3() with WordPress 4.4

[fklein-lu]

The according to the documentation, the filter_sideload_move_temp_file_to_s3() method of S3_Uploads exists to work around Core bug #29257.

This issue is marked as fixed for 4.4, so we should review whether we still need this method in the plugin. If we end up removing the plugin's method, we should put a check for the WordPress version requirement in place, and document this, similar to #69.

[lightningspirit]

In a recent installation with PHP 7.4 and WordPress 5.4.2, and using version 2.2.2 of S3-Uploads, I had to comment lines 55 and 66 to make sideload work.

FastCGI sent in stderr: "PHP message: PHP Warning:  copy(): The second argument to copy() function cannot be a directory in /<path-to-wp>/wp-content/plugins/s3-uploads/inc/class-s3-uploads.php on line 226" while reading response header from upstream, client: [REDACTED], server: [REDACTED], request: "POST /uploader HTTP/2.0", upstream: "fastcgi://unix:/run/php/php7.4-fpm.sock:", host: "[REDACTED]", referrer: "[REDACTED]"

[phpanos]

Any update on this? Still getting the issue using function "media_handle_sideload". At the moment we forked the plugin and removed the filter which solves our issue.