feat: Add recent sprite changes as a mainline mod

[thedyze]

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Purpose of change

There were wishes from parts of the community to be able to keep using UDP in it's original state in a convenient manner. The purpose of this PR is to move recent sprite changes into a mod.

Describe the solution

This change adds the following PRs as a mod:

Portal animation #5640
Extended sidewalk visuals #5657
New brick wall sprites #5664
New/updates door sprites #5674
New cursor sprites #5689
New floor sprites #5690
New run/crouch icons #5692

For sake of simplicity when reviewing/migrating, most of the sprites have not been moved from their sprite indexes, which leaves some empty spaces in the images. I intend to fill in these as work continues.
There are some very minor changes to the sprites, the most dramatic being a revert to using a tweaked version of the original "boarded up boards", was not quite satisfied with the ones I'd created. Saturation has also been dialed back one small notch on many sprites. A single addition is the multiple items on a tile + sign. Has been shrunk very slightly, otherwise looks as the original.

This change doesn't remove the currently merged sprite changes. I wanted this verified working before any removal.
So either the merger removes the current stuff once tested or, alternatively I'll post a follow up PR once this is approved.
Mod documentation will follow.

Describe alternatives you've considered

Testing

Going through all tiles using the map editor.

Additional context