Fix cooldown swipe direction: decide per icon category

[choppaoops]

Problem

ApplyCooldownSwipe sets the swipe reverse from a single global
reverseActiveSwipe toggle. No single value is correct for every icon, because
the categories want different directions:

• Buff icon viewers (SCMBuffOptions) read best counting down
  bright → dark — the dark swipe grows as the buff expires.
• Icons showing an active aura use Blizzard's native active swipe, which
  already shrinks to show remaining time. They must not be reversed —
  reversing makes the highlight grow instead of shrink.
• Icons on cooldown count down dark → bright.

With one global flag, enabling it fixes buff icon viewers but flips the active
swipe the wrong way; disabling it does the reverse. There is no setting that gets
both right.

Fix

Decide the reverse value from the icon category instead of the global flag. Only
buff icon viewers reverse; icons showing an active aura and icons on cooldown keep
the default direction:

local isBuffViewer = parent.SCMBuffOptions and true or false
-- ... in the aura / buff branch:
cooldownFrame:SetReverse(isBuffViewer)
-- ... on-cooldown branches:
cooldownFrame:SetReverse(false)

Color handling (recolorActiveSwipe, recolorNormalSwipe, the color pickers,
disableRegularIconActiveSwipe) is unchanged — this only touches direction.

Notes

• The reverseActiveSwipe option is no longer read; its checkbox can be removed
  from the options panel (or kept as a no-op). No defaults change is required.
• Verified on Essential / Utility / BuffIcon viewers: icons on cooldown sweep
  dark→bright, buff icon viewers sweep bright→dark, and the native active swipe
  shrinks correctly.