"unrestricted" number of custom palettes (#4932)

- allow more than 10 custom palettes
- move palettes into CPP file
- Fix for minimizing cpal.htm (saves 2k of flash)
- shortened names in cpal, saves about 400 bytes of Flash after packing
- removed async from common.js loading to prevent errors on page loads if the file is not cached
- restricted nubmer of user palettes on ESP8266 to 10
- unrestricted number of user palettes on all other platforms (total max palettes: 256)
- added a warning when adding more than 10 palettes to let the user decide to risk it
- Bugfixes in palette enumeration, fixed AR palette adding
- AR palettes are now also added if there are more than 10 custom palettes

Co-authored-by: Blaž Kristan <blaz@kristan-sp.si>

usermods/audioreactive/audio_reactive.cpp

@@ -1981,7 +1981,7 @@ void AudioReactive::createAudioPalettes(void) {
   if (palettes) return;
   DEBUG_PRINTLN(F("Adding audio palettes."));
   for (int i=0; i<MAX_PALETTES; i++)
-    if (customPalettes.size() < 10) {
+    if (customPalettes.size() < WLED_MAX_CUSTOM_PALETTES) {
       customPalettes.push_back(CRGBPalette16(CRGB(BLACK)));
       palettes++;
       DEBUG_PRINTLN(palettes);