Add blit caching and blend modes to Brush tool (#1268)

Added blit caching.

Added bulk memory target feature.

Added brush texture caching.

Removed dead format call.

Fix brush_texture_cache crashing on serialization.

node-graph/gcore/src/raster.rs

@@ -11,6 +11,7 @@ pub mod adjustments;
 pub mod bbox;
 #[cfg(not(target_arch = "spirv"))]
 pub mod brightness_contrast;
+pub mod brush_cache;
 pub mod color;
 pub mod discrete_srgb;
 pub use adjustments::*;