xe driver for Lunar Lake, Battlemage and Panther Lake #8

i915 stops at Meteor/Arrow Lake and DG2; Xe2 and Xe3 exist only in Linux's xe driver, which has never run outside Linux. Plan: import xe from Linux 6.14 the way NullMoth's port did (GPL-only files stripped, xe_pt_walk.c replaced), on the same DRM core, after i915 works. GuC is mandatory there.