[oUF] Upstream updates:

- Use RegisterUnitEvent to replace home-brew event dispatcher.
- healprediction: add a .frequentUpdates option.
- Reduced copy-pasta in classicons.
- Hide on disable
- Altpowerbar tweaks
- Color gradient based on hue/chroma/luma (HCY)
[oUF_Neav] Enable frequentUpdates for heal prediction.
[oUF_NeavRaid] Enable frequentUpdates for heal prediction.
[oUF_NeavRaid] Remove old spell.
[oUF] Fixes for Show/Hide errors.
[oUF_Neav] Add absorb bar.

Applies to player, target, focus and pet