Add a dedicated error for include = "dev" with tool.uv.dev-dependencies (#9173)

## Summary

This isn't really spec-compliant, so we already don't allow it -- this
just adds a better error message and an explicit test for it.

crates/uv-workspace/src/workspace.rs

@@ -343,7 +343,8 @@ impl Workspace {
 
             // Resolve any `include-group` entries in `dependency-groups`.
             let dependency_groups =
-                FlatDependencyGroups::from_dependency_groups(&dependency_groups)?;
+                FlatDependencyGroups::from_dependency_groups(&dependency_groups)
+                    .map_err(|err| err.with_dev_dependencies(dev_dependencies))?;
 
             // Concatenate the two sets of requirements.
             let dev_dependencies = dependency_groups