First BG EUV Graphic Content update

Graphics
- replaced existing auxiliary donkey with new graphic look: instead of only seeing the auxiliary donkey unit, you will see an animated flag-bearer with dynamically changing coat of arms and donkey unit together marching with your army.
- New Byzantine army unit flavor for Age I incl new textures + 3D model: new cataphract horse armor, varangian guard torso, legs and 4 different new headgear for varangian guards/cataphracts/byzantine heavy units
- reworked/polished 3D army unit model weapons: longsword, shortsword and spear
- added custom high uniformity look for HAB (Austria) Age II regular units (based on existing + polished assets)

*initial upload (of empty placeholder version)