Below the Surface - modify lives indicators and HP bars

[MHLoppy]

This PR was also worked on by zhusim222. (we collaborated off-git, so unfortunately he doesn't show as a contributor by default)

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Description

Updates the lives indicators and HP bars for players in both 1P and 2P modes for the sake of both clarity and aesthetics:

• Removes the face attached to each HP bar in order to improve readability
• Adds a darkened border to HP bars (midpoint between black and that player's "HP color")
• Makes HP bar colors consistent between full and empty
• Discretizes HP bars (they now have markers for each of the player's 3 HP)
• Swaps lives indicators from helmets to faces
• Minor additional art/code changes to support the above changes
• (now-legacy art files have been moved to a new subfolder in case they're wanted in the future)

Composite screenshot below (the "1P" and "2P" are not part of the changes)

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

The game was rebuilt and run in both 1P and 2P modes. Damage was taken to test the HP bars at each level of HP. Screenshots were taken and examined to verify alignment of the modified sprites.

Testing Checklist

• Tested in 1P mode
• Tested in 2P mode

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I will mark this work as ready for peer review

[MHLoppy]

Just to make it as clear as possible I'll copy this into a separate comment too:

This PR was also worked on by zhusim222. (we collaborated off-git, so unfortunately he doesn't show as a contributor by default)

[MHLoppy]

Below The Surface - update HP bar UI

[zhusim222]

the final changes look amazing! definitely an upgrade from the original health bars, especially the partitions where the player can easily tell their current HP and lives