Enhance types generation

[DemianParkhomenko]

Is your feature request related to a problem? Please describe.

Currently, all types are optional, or at least a lot of them. See: https://github.com/search?q=repo:googleapis/google-api-nodejs-client+%22%7C+null%22&type=code So, this leads to an awful development experience.

For example, see Google Calendar API:

https://github.com/googleapis/google-api-nodejs-client/blob/6e8c998cee93dbc79a6f306c2150414b933c22c9/src/apis/calendar/v3.ts#L720

But on the other hand, we can see in docs that some fields are optional and some are not.

https://developers.google.com/calendar/api/v3/reference/events#resource

Describe the solution you'd like I would like to see real types with the minimum amount of optional fields.

Describe alternatives you've considered Of course, we can check everything manually or disable TypeScript checking at all. But I believe it's not a good solution, as why do we need typings which do not work. https://github.com/googleapis/google-api-nodejs-client/issues/3151