Add Litematica exporter and integrate serde for serialization

- Introduced Litematica exporter with necessary data structures for Minecraft text generation.
- Added serde dependency for serialization support in multiple crates.
- Updated Cargo.toml files to include new dependencies and features.
- Created palette module for block palette management.

crates/exporters/src/lib.rs

@@ -1,3 +1,4 @@
+mod litematica;
 mod mcfunction;
 
 pub use mcfunction::McFunctionExporter;