feat(test runner): advanced error representation

[dgozman]

• Use util.inspect() to print errors like Node.js does, which includes any custom properties on the error object and standard cause property for inner errors.
• Move test runner stack trace filtering to serializeError().
• Move common stack trace filtering to parseStackTraceLine().
• Simplify reporters handling errors.
• Small tweaks for nicer representation.
• API change: TestError.message is now a formatted message with properties, TestError.stack is just a stack without message.