fix(sql-backend-handler): enable lldap_domain "test" feature in dev-deps

lldap_domain::JpegPhoto::for_tests() and uuid helpers are gated behind
the "test" feature on the lldap_domain crate. The sql-backend-handler
dev-deps did not enable that feature, causing ~12 compilation errors in
sql_user_backend_handler.rs and sql_tables.rs when building the test
binary. This unblocks cargo test -p lldap_sql_backend_handler --lib.

crates/sql-backend-handler/Cargo.toml

@@ -71,6 +71,10 @@ path = "../domain-model"
 [dependencies.lldap_opaque_handler]
 path = "../opaque-handler"
 
+[dev-dependencies.lldap_domain]
+path = "../domain"
+features = ["test"]
+
 [dev-dependencies.lldap_test_utils]
 path = "../test-utils"