Media REST API: Fix sideload and finalize for EXIF rotated images

[adamsilverstein]

Backport of WordPress/gutenberg#80295 (part of WordPress/gutenberg#77582).

Problem

In the client-side media upload flow, the client uploads the original file unmodified, applies the EXIF rotation itself, and sideloads the rotated file with image_size=original. For quarter-turn orientations (EXIF 5-8) the rotated file's width and height are swapped relative to the stored metadata, so validate_image_dimensions() rejected the sideload with a 400 (rest_upload_dimension_mismatch) and the upload failed.

The original sideload also stored the rotated file as original_image while the un-rotated upload stayed the attachment's main file, which is backwards relative to what core does when it rotates on upload.

Solution

• Treat an image_size=original sideload like a scaled sideload: the supplied (rotated) file replaces the attachment's main file, and the untouched upload is kept as original_image. This mirrors the swap _wp_image_meta_replace_original() performs in wp_create_image_subsizes().
• Accept transposed dimensions when validating an original sideload.
• Reset the stored EXIF orientation to 1 in finalize for both original and scaled sub-sizes, as wp_create_image_subsizes() does for its scale and rotate paths, so exif_orientation no longer reports the pre-rotation value once rotation has been applied.
• Skip original/scaled finalize entries missing the file name so a malformed payload cannot blank out the main file metadata.

Includes a parity test asserting the client-side path produces the same attachment metadata (dimensions, orientation, original_image) as a classic server-side upload of the same EXIF-rotated fixture.

Trac ticket: https://core.trac.wordpress.org/ticket/65643

Commit message

Media REST API: Fix sideload and finalize for EXIF rotated images.

Fix an issue where client-side media uploads of JPEGs with a quarter-turn EXIF orientation (values 5-8) failed with a 400 `rest_upload_dimension_mismatch` error, because the rotated file's swapped width and height did not match the stored metadata.

An `image_size=original` sideload is now handled like a `scaled` one: the rotated file becomes the attachment's main file and the untouched upload is kept as `original_image`, matching what core does when it rotates on upload. Finalize also resets the stored EXIF orientation once rotation has been applied.

Follow-up to [61982], [62619].

Props adamsilverstein, andrewserong, ramonjd.
Fixes #65643.

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Props adamsilverstein, andrewserong.

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[andrewserong]

Thanks for opening this! It's a faithful backport of WordPress/gutenberg#80295 and I manually tested that this works as expected with the rotated file saved as the main source_url / media_details.file, with the original file as original_image.

LGTM!