Provide tutorials scenes for basic operations

[fire]

Similar to https://github.com/QodotPlugin/qodot-plugin/tree/master/addons/qodot/example_scenes

Visual

0-structural-geometry 1-textures 2-materials 3-auto-pbr 4-special-textures 5-baked-lighting

Interactive

0-point-entities 1-brush-entities 2-worldspawn-layers 3-basic-signal-wiring 4-advanced-signal-wiring

Misc

0-group-hierarchy 1-runtime-map-building