Add `` to "default" Swift enum value

[liangdrime]

TypeScript enum value DEFAULT was converted to default in Swift, that caused a naming conflict issue.

To fix it, adding `` to default value of Swift enum while transforming it from ts to Swift.

[haven2world]

Could you add this case into the demo/basic/interfaces.ts and run npm run start:example:basic to generate the code

[liangdrime]

Could you add this case into the demo/basic/interfaces.ts and run npm run start:example:basic to generate the code

Added!