port GemRB_Window_SetupEquipmentIcons to ActionsWindow.py

It's the only non-helper leftover of the hardcoded actions bar. Looking at what it does, it looks doable with only minor tweaks needed. For example `GemRB_GetItem` will need to expose more `ExtHeader` fields, the picture handling might require another cycle param elsewhere and so on.

Start by comparing the existing GemRB_Window_SetupEquipmentIcons implementation with ActionsWindow.py and trace the hardcoded actions-bar helpers it depends on. Check the GemRB_GetItem interface and the picture handling path, then confirm the port works with the additional ExtHeader fields and any required cycle parameter.

Written by the indexing model from the issue text.