Enumerates SkAdNetwork ad event types

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v26/enums/sk_ad_network_ad_event_type.proto)

| Enums ||
|---|---|
| ## `INTERACTION` | The user interacted with the ad. |
| ## `UNAVAILABLE` | The value was not present in the postback or we do not have this data for other reasons. |
| ## `UNKNOWN` | The value is unknown in this version. |
| ## `UNSPECIFIED` | Not specified. |
| ## `VIEW` | The user viewed the ad. |