Reversed deprecations for Image constants, except for duplicate Resampling attributes

[radarhere]

Resolves #6537

The user in the issue found a warning that Image.BILINEAR is deprecated, and questions whether it is necessary to deprecate this.

This PR removes the deprecation warnings for Image.* constants added in #5954 (and released in Pillow 9.1.0).
However, there are three exceptions - I've left LINEAR, CUBIC (which have been duplicates of other constants since PIL) and ANTIALIAS (which has been a duplicate since #1028) deprecated.

I'm also leaving the deprecations for ImageCms, ImageFont, BlpImagePlugin, FtexImagePlugin and PngImagePlugin in place.

See what you think of this.

[hugovk]

Thanks for picking this up. Looks fine, let's keep this open a few days and merge before January if there's no strong objections.

Let's also mention it in the release notes, and add a note (with .. note:: ?) to https://pillow--6830.org.readthedocs.build/en/6830/deprecations.html#constants to mention that some had been deprecated but are no longer.

Also, I wonder if we should somehow mention it at https://pillow--6830.org.readthedocs.build/en/6830/releasenotes/9.1.0.html#constants? These are historical, but perhaps some sort of note, even if just a link to the 9.3.0 notes, could help?

[radarhere]

Ok, I've added a commit to update the documentation.

[hugovk]

Wonder if something like this is clearer?

Suggested change

	In Pillow 9.1.0, the following constants were deprecated. Those deprecations have now
	been restored.
	In Pillow 9.1.0, the following constants were deprecated.
	That has been reversed and these constants will now remain available.

[radarhere]

Ok, sure. I've pushed a commit changing that, and the text in deprecations.rst.