Replace HookAddonOrVariable with an EventUtil-based HookAddon

The polling lurker frame is gone. HookAddon gates on
C_AddOns.DoesAddOnExist, waits for PLAYER_LOGIN with
EventUtil.ContinueOnPlayerLogin, then runs on
EventUtil.ContinueOnAddOnLoaded. Addons loaded at startup still hook
only after every pfUI module and skin exists and after the addon's
own VARIABLES_LOADED setup. Load-on-demand addons still hook on their
ADDON_LOADED.

The "or variable" form is gone. Callers that passed a global now pass
the addon that defines it: TheoryCraft, SuperMacro, DPSMate and
Turtle_GroupUI. DPSMate names its windows from its settings, so its
hook now checks for DPSMate_DPSMate itself, as the variable lookup
used to. eqcompare's Guda check uses HookAddon too.

modules/turtle-wow.lua

@@ -61,7 +61,7 @@ pfUI:RegisterModule("turtle-wow", function ()
       end
     end
 
-    HookAddonOrVariable("GroupFrame", function()
+    HookAddon("Turtle_GroupUI", function()
       -- After Turtle's own init, hide frames if pfUI handles them
       hooksecurefunc("GroupFrame_Toggle", function()
         if pfUIHandlesGroupOrRaid() then
@@ -268,7 +268,7 @@ pfUI:RegisterModule("turtle-wow", function ()
   if pfUI.skin["Inspect"] and pfUI_config["disabled"]["skin_Inspect"] ~= "1" then
     local initialized = false
 
-    HookAddonOrVariable("Blizzard_InspectUI", function()
+    HookAddon("Blizzard_InspectUI", function()
       hooksecurefunc("InspectFrame_Show", function()
         -- break if theres nothing left to do
         if initialized then return end
@@ -326,7 +326,7 @@ pfUI:RegisterModule("turtle-wow", function ()
   end
 
   -- rearrange twow's profession window additions
-  HookAddonOrVariable("Blizzard_TradeSkillUI", function()
+  HookAddon("Blizzard_TradeSkillUI", function()
     if TradeSkillSkillCheckButton and pfUI.skin["Profession"] and pfUI_config["disabled"]["skin_Profession"] ~= "1" then
       SkinCheckbox(TradeSkillSkillCheckButton)
       TradeSkillSkillCheckButton:SetWidth(24)
@@ -348,7 +348,7 @@ pfUI:RegisterModule("turtle-wow", function ()
   end)
 
   if C.disabled["macroicons"] == "1" then
-    HookAddonOrVariable("Blizzard_MacroUI", function()
+    HookAddon("Blizzard_MacroUI", function()
       if type(UpdateMacroIconFilenames) ~= "function" then return end
       function _G.UpdateMacroIconFilenames()
         wipe(MACRO_ICON_FILENAMES)