Fix missing papyrus in savanna, add a dry dirt version

Fix missing papyrus in savanna, add a dry dirt version

Papyrus was missing from the dry dirt 'savanna_shore' biome due to
only being placed on dirt. A mistake made when changing savanna
dirt to dry dirt.

Rename existing papyrus schematic to 'papyrus_on_dirt' and only
place in the 'rainforest_swamp' biome.
Add a new papyrus schematic 'papyrus_on_dry_dirt', placed in the
'savanna' biome.