[M1] add util::Error, Result<T>, format()

tests/CMakeLists.txt

@@ -0,0 +1,10 @@
+find_package(Catch2 3 REQUIRED CONFIG)
+include(Catch)
+
+function(cargoxx_add_test name)
+    add_executable(${name} ${name}.cpp)
+    target_link_libraries(${name} PRIVATE cargoxx Catch2::Catch2WithMain)
+    catch_discover_tests(${name})
+endfunction()
+
+cargoxx_add_test(util_error)