project: enable missing project_core/test-support feature when test-support is enabled (#8471)

This fixes collab's test build failure that @ConradIrwin spotted.


Release Notes:

- N/A

crates/project/Cargo.toml

@@ -16,6 +16,7 @@ test-support = [
     "settings/test-support",
     "text/test-support",
     "prettier/test-support",
+    "project_core/test-support",
     "gpui/test-support",
 ]