Feature walks: generate them from field roles with #[derive(Walk)] (#1251)

The three walks over a feature (expressions, references, geometry) are generated from FeatureKind by #[derive(Walk)] in a new proc-macro crate, solidcraft-derive, from #[walk(...)] attributes written next to each field. The hand-written walks in params.rs, feature_refs.rs and feature_geometry.rs are gone; Ruled Surface and Extend have their attributes, and the three golden walk records are unchanged.

Co-authored-by: jijinbei <jijinbei@users.noreply.github.com>

crates/derive/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "solidcraft-derive"
+description = "SolidCraft derive macros: the walk over a feature's geometry, from role attributes on its fields"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[lib]
+proc-macro = true
+
+[lints]
+workspace = true
+
+[dependencies]
+proc-macro2 = { workspace = true }
+quote = { workspace = true }
+syn = { workspace = true }