fix tooltip widget set taint

[mjodheim]

What changed

Wrap Retail GameTooltip_AddWidgetSet so ElvUI calls Blizzards original implementation through securecallfunction.

Why

Some tooltip widget sets can expose secret values while Blizzard lays out UI widgets. When GameTooltip_AddWidgetSet runs in an ElvUI-tainted execution path, Blizzard code can crash while doing arithmetic on those secret values, for example:

Blizzard_UIWidgetTemplateTextWithState.lua:35: attempt to perform arithmetic on local `textHeight` (a secret number value, while execution tainted by `ElvUI`)

Calling the original Blizzard function through securecallfunction avoids carrying ElvUI taint into the widget processing path, without suppressing any widget set or hiding tooltip content.

Reproduction observed

• Retail
• Hovering an Area POI story variant tooltip with widgetSetID 1273
• Stack path: GameTooltip_AddWidgetSet -> UIWidgetManager:RegisterForWidgetSet -> TextWithStateWidget:Setup

Validation

• git diff --check
• Applied locally and intended for in-game verification with /reload plus the affected Area POI hover path