Pick cooldown timers per feature with one dropdown

Each feature's settings page now picks its own timers - None, Numbers,
Sweep, or Numbers And Sweep - in place of the "Show Numbers On", "Show
Sweep On" and "Reverse Sweep On" lists on Settings -> Cooldown. Unit
frames get theirs per frame again ("Buff And Debuff Timers" and
"Indicator Timers"), so party and pet can drop their numbers while the
target keeps them. The other dropdowns sit on Action Bars, Bags & Bank,
Buff/Debuff Icons, Totem Icons, Tooltip and Nameplates.

Settings -> Cooldown keeps the shared font, size, threshold, tenths and
colors, plus the timers of Spellbook And Character, Loss Of Control and
Other Addons, which have no page of their own.

CreateCooldown(parent, kind, config, key, name) reads its mode from
config[key]. The kind says only what it times: "spell" hides numbers on
the global cooldown, "aura" drains its sweep, "timer" fills it. The
reverse option is gone; the direction follows the kind.

The migration carries every old setting into its timers: the
C.cooldown kind tables, appearance.cd's foreign and Blizzard toggles,
the buff frame's sweep, the nameplate debuff options, and each unit
frame's timer text, sweep and "Show Time Left" from before the kinds,
so frames that had their own settings keep them. Reverse options are
dropped.

modules/buff.lua

@@ -152,7 +152,7 @@ pfUI:RegisterModule("buff", function ()
 
     -- the sweep and the duration numbers (the template covers the button and
     -- starts hidden); RefreshBuffButton starts its timer
-    buff.cd = CreateCooldown(buff, "buff", buttonName .. "Cooldown")
+    buff.cd = CreateCooldown(buff, "aura", C.buffs, "timers", buttonName .. "Cooldown")
     buff.cd:SetFrameLevel(buff:GetFrameLevel() + 1)
     buff.overlay:SetFrameLevel(buff:GetFrameLevel() + 2)