New entry point for drawing overlay icons

[ssj17vegeta]

What does this PR do?

This PR integrates a new entry-point that allows plugging third-party addons like CanIMogIt (which draws a small icon representing whether items can be transmogged) with EllemereUI's bags.

See the compatibility patch for its intended use-case.

Without having both CanIMogIt and its compatibility patch I made, the modification does nothing (since EUI_Bags.itemOverlayIcons == {} thus the loop gets out immediately).

How was it tested?

Latest live Midnight build as of September 11th 2026.

Basically, have a transmoggable/collectible item in your bag, CanIMogIt's transmog-status icon should appear if you have CanIMogIt and its compatibility patch installed.

Tests made : not-transmogged item bought, switched it between bank, guild bank, different bags, icon shows up fine in own bag, no LUA error, no perceivable slowdown.

Screenshots

Checklist

• New settings default OFF (no behavior change without opt-in)
• Zero cost while disabled: no events registered, no polling, no hooks doing work, no frames built
• Cheap while enabled: event-driven (no polling, no timer-based logic, no per-frame allocations)
• No writes onto Blizzard-owned frames (weak-table pattern used); HookScript/hooksecurefunc only, never SetScript on Blizzard frames
• Tested in-game on live; no version gates or pre-Midnight APIs added