Custom Flamer Tanks (And Why They Don't Work)

### Testmerges

N/A

### Description of the bug

Flamer tanks made by Ordnance Technicians sound good on paper, but are currently sadly not worth the metal and effort they cost. There's a plethora of issues which relate to them, of which are:

1. M240-T Fuel Tanks can't be used by the pyrotechnician specialist. There is no way to attach custom fuel tanks to the Broiler-T flexible refueling system.

2. Some chemicals which should work with custom fuel tanks, don't. I've tried to make sense of this, but I simply couldn't. Phosphorus with an intensity of 1i/u can't be used to refill custom fuel tanks, but Methane with an intensity of -0.35i/u can.

3. You can't use the chemical tanks (apart from the Welder Fuel one) in the OT Workshop to refuel custom fuel tanks - they don't count as reagent tanks, which only further frustrates pyro-interested Ordnance Technicians.

4. The "unit of fuel / tile" maths make no sense. You have regular flamer fuel tanks shoot 5 tile long flames for 5 units of fuel (1u/t), but to reach the same amount of tiles with any other custom fuel, you need to use 25 units of fuel (5u/t). And if you try to use 1u/t, you get just that - a single tile in front of you. That means that every """good""" fuel tank only has 4 uses ("""good""" as in, literally no different to the standard UT-Napthal you get in regular incinerator tanks, compared to Napalm which takes time and effort to make).

5. You can not mix fuels. Whilst technically not a bug, I do not know why this is a thing to begin with. The only explanation I have for this is that whoever was making custom flamers didn't want to deal with coding it at the time - which is totally understandable. But the first thing every Ordnance Technician tries is literally that; try to mix fuels. This is just a sad kick in the nuts.

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

[1]
Currently: M240-T Fuel Tanks can not be attached to the Broiler-T flexible refueling system.
Expected: M240-T Fuel Tanks can be attached. You can switch between a single custom fuel tank, and the 3 regular ones.

[2]
Currently: Chemicals which should work, don't. Chemicals which shouldn't work, do.
Expected: Every chemical should be able to be put into fuel tanks. There should be either no flames or a minimum amount of flames upon trying to use a flamer in a scenario where the chemical is unsuitable. Ergo, minimum intensity, minimum range, minimum duration (as it currently works for every custom explosive casing).

[3]
Currently: Trying to use the custom fuel tank on the roundstart oxygen tank doesn't work. Putting the oxygen into a seperate tank and then trying to refuel the custom fuel tank does work.
Expected: Custom fuel tanks can be refilled at roundstart chemical tanks in the Ordnance Technician Workshop.

[4]
Currently: 1u/t translates to 1 tile of flames for custom fuel tanks, and 5 tiles of flames for regular UT-Napthal incinerator tanks. The damage for both (in the scenario of using custom made Napalm) is the same, the ammo consumption is not.
Expected: Custom fuel tanks should be, at the very least, slightly better than regular incinerator tanks to warrant their use/time it needs to make them. 1u/t translates to 5 tiles of flame, same as it does for regular incinerator tanks.

[5]
Currently: to_chat(user, SPAN_WARNING("You can't mix fuel mixtures!"))
Expected: to_chat(user, SPAN_WARNING("Hey, go batshit insane on that fuel mix!"))

### How do we reproduce this bug?

[1]
Any attempt to put the large fuel tank into the pyro specialist's Broiler-T flexible refueling system.

[2]
Any attempt to refuel with a phosphorus reagent tank.
Any attempt to refuel with a methane reagent tank (other than the one in OT workshop, see [3]).

[3]
Any attempt to refuel with a roundstart reagent tank in OT Workshop.

[4]
Comparing custom fuel tanks and regular incinerator tanks, with varying fuel consumption, make the nonsense apparent.

[5]
Mixing fuel mixes, trying to use the mixed fuel mixes, getting sad over not being able to make custom fuel mixes. :(

### 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)