Use the same vanilla terminology for biome blend option in config screen

[MeeniMc]

Use the same vanilla terminology for biome blend option in config screen
(e.g., 5x5 is a radius of 2)

[MeeniMc]

Updated according to discord discussion. "[...] but it should just be implemented using a custom formatter (manipulating the actual config value like that is problematic)".

2 notes:

1. When using the shift-p vanilla screen, it would be possible to set blending radius to 0. The resulting Sodium configuration works. Solution: I let the Sodium slider take the 0 input, and clarified in the tooltip that this case is not blended, but still smoothed.
2. It was not clear to me what was 'problematic' with the prior approach. The value in the config file, and in the rest of the codebase would still be expressed in radius (unchanged from prior versions of Sodium, that is, 2 for the 5x5 case). I did the requested changes anyway, thus when holding the slider widget, it will now show the radius value, but we still clarify how e.g., 2 is equivalent to 5x5 Vanilla nomenclature when the widget is not held.