Gravity Adaptations Bioaug (#21532)

From the list of bioaugments requested by Schwann.
https://docs.google.com/document/d/1SLbll969PyJ_H9J1LP8cmdso9OMozUc8MGOVZkY4HbE/mobilebasic

Gravity Adaptations are a bioaugment that serves as an implanted
alternative to legbraces, which grant the same effect. These are unique
to Galatean Offworlders in the same vein as legbraces being unique to
offworlders. They also essentially have the same effect, making the
offworlder immune to the effects of "Gravity Weakness". To make this
work, I refactored the gravity weakness mechanic to operate via a
signal, which has a shared response between legbraces and gravity
adaptations. This "Cancelable signal" pattern is going to be fairly
common going forwards as I refactor a variety of systems to allow far
greater degrees of unique interactions, without the need of hardcoding
said interactions at the source.

<img width="797" height="84" alt="image"
src="https://github.com/user-attachments/assets/01622f2b-56a1-4fb8-ae43-d78afd35f3b5"
/>

<img width="935" height="91" alt="image"
src="https://github.com/user-attachments/assets/309bbc66-d6aa-44b1-9a59-64f7fc800c90"
/>

<img width="617" height="259" alt="image"
src="https://github.com/user-attachments/assets/81a1f973-b1af-45c1-8373-05549fde286a"
/>

I have tested this PR and have verified in my dev environment that it
works as advertised.

code/game/objects/items/devices/augment_implanter.dm

@@ -80,6 +80,9 @@
 /obj/item/device/augment_implanter/auxiliary_heart
 	new_augment =	/obj/item/organ/internal/augment/bioaug/auxiliary_heart
 
+/obj/item/device/augment_implanter/gravity_adaptations
+	new_augment =	/obj/item/organ/internal/augment/bioaug/gravity_adaptations
+
 /obj/item/device/augment_implanter/mind_blanker
 	new_augment =	/obj/item/organ/internal/augment/bioaug/mind_blanker