Make rainbow effects more colorful (#3681)

* Make color_wheel rotate in HSV sapce instead of linearly interpolating R->G->B
* Remove the rainbow wheel option, as that is the same as the rainbow palette
* Use hsv2rgb for color_wheel

This is the current result of the discussion in https://github.com/wled/WLED/pull/3681

wled00/cfg.cpp

@@ -519,7 +519,6 @@ bool deserializeConfig(JsonObject doc, bool fromFS) {
   CJSON(briMultiplier, light[F("scale-bri")]);
   CJSON(paletteBlend, light[F("pal-mode")]);
   CJSON(strip.autoSegments, light[F("aseg")]);
-  CJSON(useRainbowWheel, light[F("rw")]);
 
   CJSON(gammaCorrectVal, light["gc"]["val"]); // default 2.2
   float light_gc_bri = light["gc"]["bri"];
@@ -1042,7 +1041,6 @@ void serializeConfig(JsonObject root) {
   light[F("scale-bri")] = briMultiplier;
   light[F("pal-mode")] = paletteBlend;
   light[F("aseg")] = strip.autoSegments;
-  light[F("rw")] = useRainbowWheel;
 
   JsonObject light_gc = light.createNestedObject("gc");
   light_gc["bri"] = (gammaCorrectBri) ? gammaCorrectVal : 1.0f;  // keep compatibility