Add option to invert the direction of the clock

[Dicebar]

On icons, the clock currently only supports filling up. In some use-cases, for instance for cooldowns, it would be nice to support the inverse, with the icon becoming more visible as the ability cools down.

For cooldowns, this is would conform to how the Blizzard UI works by default. So it might be interesting to make this the default behavior for cooldowns, while retaining the current behavior for auras.

Solution:

• Add an option at bar groups to invert the clock.
• Differentiate behavior per bar type.