Move "max fuel" input to character tab and rename "max moves"

[faucomte97]

Task Description

The level editor feature in Rapid Router allows for the creator to set a specific amount of "fuel" for the van - this is a useful game mechanic especially when creating a level that highlights the need to write efficient code / find an efficient route.
The input for that setting currently lives under the "Map" tab. It should be moved to the "Character" tab instead as it relates more to the character "moving" around the map.

Additionally, "fuel" only refers to the classic van character and doesn't make sense when another character is chosen, so we want to rename the label of the input.

Acceptance Criteria

• Move the "fuel" input from the "Map" tab to the "Character" tab.
• Rename the input from "Max fuel" to "Max moves" (this is only needed on the frontend side, for simplicity's sake, the variable in the code can remain fuel as renaming it everywhere would be tedious.)

[libklein]

Happy to work on this @faucomte97 .

[faucomte97]

Good place to start looking: https://github.com/ocadotechnology/rapid-router/blob/master/game/templates/game/level_editor.html