Filter UNIT_AURA by unit token and drop the unit streams in realtime mode

Two handlers opened by testing arg1 against a fixed set of unit tokens, so
every other unit's copy of UNIT_AURA reached Lua only to be compared away
-- in a raid that is the bulk of them. ClassicAPI's RegisterUnitEvent
pushes that filter into the client, so the handler only runs for the units
named. Filtering is per (frame, event), so the other events sharing the
libdebuff frame are unaffected.

  Utility.lua      UNIT_AURA -> "target"            (libdebuff seeding)
  ComboPointTracker UNIT_AURA -> "target", "player"

Extensions register through CleveRoids.RegisterEvent, so ExtensionsManager
gains a RegisterUnitEvent alongside it.

Separately, the main frame's unit state streams (UNIT_AURA / UNIT_HEALTH /
UNIT_POWER, or the _GUID variants under Nampower v2.39+) are now registered
only in event-driven mode. Their handlers are wholly wrapped in
`realtime == 0`, so with realtime on every one of them crossed into Lua and
returned immediately while the OnUpdate did the refreshing. Registration is
applied at load, again at VARIABLES_LOADED once the saved setting is
readable, and whenever /cleveroid realtime flips it.

Those three stay plain RegisterEvent calls: their handlers ignore the unit
and refresh every macro, and a conditional may name any unit
([@party3,hp:<50], @focus, @mouseover), so narrowing the token set would
leave those icons stale. The _GUID variants could not be filtered anyway --
their first argument is a GUID, not a unit token.

ComboPointTracker.lua

@@ -745,7 +745,7 @@ function Extension.OnLoad()
     Extension.RegisterEvent("SPELLCAST_FAILED", "OnSpellcastFailed")
     Extension.RegisterEvent("SPELLCAST_INTERRUPTED", "OnSpellcastInterrupted")
     Extension.RegisterEvent("PLAYER_TARGET_CHANGED", "OnTargetChanged")
-    Extension.RegisterEvent("UNIT_AURA", "OnUnitAura")
+    Extension.RegisterUnitEvent("UNIT_AURA", "OnUnitAura", "target", "player")
     Extension.RegisterEvent("PLAYER_COMBO_POINTS", "OnComboPointsChanged")
 
     -- PERFORMANCE OPTIMIZATION: Removed OnUpdate polling for combo points
@@ -765,10 +765,10 @@ function Extension.OnTargetChanged()
     CleveRoids.UpdateComboPoints()
 end
 
+-- Registered as a unit event for target and player, so arg1 is always one of
+-- those two -- no token check needed.
 function Extension.OnUnitAura()
-    if arg1 == "target" or arg1 == "player" then
-        CleveRoids.UpdateComboPoints()
-    end
+    CleveRoids.UpdateComboPoints()
 end
 
 function Extension.OnComboPointsChanged()