This is just grabbing the WPR2X code that was deleted. It's no longer wired into our stuff, so it won't do anything yet.

PHPCS - update minimum PHP version to 7.0
Rename wp-retina-2x classes to PerfectImages and add namespace
Add PerfectImages namespace to composer PSR4
Use new class names in 3rd-party PerfectImages loader file
Add PerfectImages fileloader to 3rd-party required files
Stop using deprecated user_can() check - use WP context user check instead
Update asset script localization to use updated enqueue

The 3 assets here were included by the previous compatibility.
(Not sure yet if we will still need them, but adding them back because they are still trying to be loaded on library page -- until we can sort it out.)

The WP min version is set in the plugin.php to 5.3 -- phpcs should match.

Add first a new property `$retina_sizes[]` to store some size info when Perfect Images generates a new retina file.

Comment out (for now) the old ajax hooks, as Perfect Image no longer uses ajax.

Add 3 methods:
1. `add_retina_sizes(int $media_id, string $retina_file, string $size_name): void` hooked to Perfect Images `wr2x_retina_file_added `, will store the media ID, retina filepath, and size name in our new `$retina_sizes` property whenever Perfect Images generates a new retina file.

2. `optimize_retina_sizes(int $media_id): void` hooked to Perfect Images `wr2x_generate_retina`, will find all the retina sizes added at the end of a Perfect Images retina generation process for a media ID (as stored in our class property) and start a new Imagify Optimization process for the newly generated retina files.

3. `add_retina_sizes_meta(array $sizes): array` hooked to Imagify's `imagify_media_files` will filter the imagify Media size meta to include the retina sizes, and flag the new sizes as being allowed to optimize.

We add 4 methods here, 2 public, and 2 private helpers:
The 2 public methods are both hooked on Perfect Images `wr2x_retina_file_removed` action.
1. `remove_retina_webp_size(int $media_id, string $retina_file ): void` will check for any webp versions of the retina file that was deleted and remove it if it exists. Note we run this even if Imagify's webp option is not currently enabled, because it may have been enabled at the time the retina was generated, and disabled since. This uses the private helper method:
2. `get_retina_webp_filepath(string $attachment_file, string $retina_file): string`. This method handles the subtask of getting the correct webp file path based on the attachment's original filepath and the retina image's filename.
3. `remove_imagify_retina_data(int $media_id, string $retina_file): void` will purge optimization data imagify uses to track the status of retina images it has optimized. Two entries have to be checked and removed for each retina image size that's been deleted: the optimization data generated when we optimized the @2x image Perfect Images created, and the @2x@imagify-webp data for the webp version (if any) that Imagify created in connection with that retina size. This uses the private helper method:
4. `get_retina_imagify_data_size_names(array $sizes, string $origina_size_name): array`. This method compares the sizes information (formatted per `wp_get_attachment_metadata()` to the original filename of an attachment that included a retina image size, and gives us an array of all the related size names that might be present in Imagify's optimization data for the attachment.

Adds a method to restore a full-size image from the backed up original.
Adds a method to replace back the previously optimized full-size image after image regeneration.
Adds a method to send regenerated images to the queue for re-optimization.

We also hook the restore/replace before and after the generation of retina sizes to insure that the original is being used to generate the retinas as well.

These were added back in on 4ffeb21  just in case. It turns out we don't need them any more.

All Perfect Images functionality is handled in the PerfectImages class now. The PerfectImagesCore is dead code.

Also, cleans up some phpcs spacing and comment formatting.

We're not going to use the related data in this case. Just get the keys and eliminate the unused variable inside foreach.

The cyclomatic complexity (and readability) of `restore_originally_uploaded_image()` was 10. All of that is due to checking the various conditions before doing the restore.

This extracts all the checking to a helper method.

Refactors the process for getting the needed webp sizes for optimization to it's own method.

For new uploads, we're going optimize everything after all the other things run their stuff.
In this case we don't want to start a proces for this media now -- doing so will "Lock" the media when the full process tries to run in a few moments, and while retinas will be processed nothing else will be included!