feat: add swamp toad spawns and functionality

[Ilwyd]

What has been done?

• Added swamp toad spawns to the swamp in north-western gnome stronghold
• Added swamp toad spawns to the lake in south-western gnome stronghold
• Added the ability to remove swamp toad legs from the toads
• Added the ability to eat toad legs

Has your code been documented?

Yes

Sources for info

https://runescape.wiki/w/Toad%27s_legs?oldid=4987128

https://runescape.wiki/w/Swamp_toad?oldid=3893849 South west stronghold spawns are not mentioned here but are present in OSRS and mentioned in a later 2014 update leading me to believe they would be there in 2011. 2014 update referenced a spawn in the middle of the south western lake which has been retained

https://oldschool.runescape.wiki/w/Swamp_toad_(item) Used for spawn locations

Respawn cycle 90 is based off of previously existing spawns for region 11573 (Taverly)