[Feature]: Prism Corner slab and related blocks

[Karpatok9089]

Describe the feature

Prism corner blocks' Flat variants (Both normal and elevated)

Blocks: Framed Flat Prism Corner (Red) Framed Flat Inner Prism Corner (Yellow) Framed Flat Elevated Prism Corner (Orange) Framed Flat Elevated Inner Prism Corner (Blue) Framed Prism Corner Slope (?) (Green) Framed Stacked Flat Prism Corner Framed Flat Inverse Double Prism Corner

[XFactHD]

These shapes are already planned, both for the Slope Slab and Slope Panel block set.