Remove FIRE_CONTAINER from oven furniture definition

Is your feature request related to a problem? Please describe.

Electric ovens IRL aren’t all that great at containing an actual fire, as they’re heat insulated with flame retardant insulation, but they’re not fireproof. Setting logs on fire in an oven would not only damage the electric heating elements and render it unusable, but it would also risk burning through the thin sheet metal bottom of the oven.

Solution you would like.

Removal of the FIRE_CONTAINER flag from f_oven. It only appears that the mapgen placed ovens are this way - the user placed oven appliance is not a fire container.

Describe alternatives you have considered.

No response

Additional context

This is an easy first issue. I can throw up a PR this weekend if nobody gets to it.