A Series of Unatomic Fire Bugfixes

[west3436]

What this does

• Items covered in ash will now retain the ash when their states are cycled (ie a lit welder will still be ashed when unlit)
• Areas should not be able to catch on fire, preventing server mustard gas.
• Held things or flaming things in a container will no longer hotspot_expose and ignite the ground beneath them.
• Fires on flammable liquids will now spread more rapidly.
• Refactored burning welding fuel puddles.

Why it's good

Closes #36534.

Changelog

:cl:

• bugfix: Items covered in ash will now retain the ash when their states are cycled (ie a lit welder will still be ashed when unlit).
• bugfix: Held things or flaming things in a container will no longer hotspot_expose and ignite the ground beneath them.
• tweak: Fires on flammable liquids will now spread more rapidly.