Pet rocks on pressure pads

What have you done in this MR?

• Add in pet rock functionality for pressure pads in waterbirth dungeon, so that players can drop a pet rock on a pressure pad to help open the door
• Source video, found by avi: https://www.youtube.com/watch?v=b_6zZnzLTZc
• Pets now all properly run away when their hunger hits 100%, instead of some of them erroneously lingering
• The pet rock will 'run away' when its hunger hits 100%. This should coincide with the pet rock item despawning from the ground.
• It is now possible to feed rocks to the pet rock. Doing so will give the player a message that the pet rock is not hungry. Source for the messages: https://runescape.wiki/w/Pet_rock?oldid=834923
• Dev mode pet hunger rate is now 10x instead of 100x

Are there any tricky things testers should keep an eye out for?

• No

• Yes, as follows:

• I have tested these changes thoroughly.

• This requires extra testing due to changes to architecture or other similarly risky changes.

• I used the Thanos Tool for any JSON edits, I did not edit any JSON files by hand (MR will be rejected if there are manual JSON edits).

• I acknowledge that this contribution will be released under the AGPL license.

Closes #640 (closed)