Absorption hearts can no longer be given unique poisoned/withered textures via resource packs

The bug

In 20w48a and prior, by modifying icons.png, it was possible for absorption hearts to be given unique textures for when under the poison or wither status effects. The regions corresponding to these hearts was left blank in vanilla (hence MC-18880), however they could be filled in with a custom icons.png (see attached) and would work as expected. However, as of 20w49a, these custom hearts will no longer be displayed, which breaks any resource packs which used this feature previously.

To reproduce in versions after 20w48a and before 23w31a, use the attached resource pack, which changes the heart texture spaces accordingly, and have absorption in combination with either wither or poison. Note how the extra hearts gain a unique texture in 20w48a, but not in 20w49a.

Note that as of 23w31a, icons.png has been split entirely. Despite this, the issue remains: there are no dedicated poisoned or withered absorption heart textured, nor does there exist a mechanism to provide them with custom textures like there used to be.

To fix this, new files must be added to the GUI HUD sprites directory specifically for absorption hearts under these effects. The code would point to these textures, giving them the correct appearence in this situation.