Getting set on fire by weaker fire, over-rides stronger fire

### Testmerges

N/A

### Round ID

N/A

### Description of the bug

If you're on fire with something stronger than say green fire, and green fire is around you can run in that to get an easy resist off of it.

### What's the difference with what should have happened?

Both fires should probably exist separately rather than any over-riding the other.
And the resists should take that into account for each fire.

### How do we reproduce this bug?

1. Be on fire by standard UT-Napthal
2. Step in some B-Gel.
3. Resist only once.
...

### Issue Bingo

- [x] Issue could be reproduced at least once
- [x] Issue happened in a recent (less than 7 days ago) round
- [x] Couldn't find an existing issue about this (https://github.com/cmss13-devs/cmss13/issues)