Api Gateway logsubscription only works with both execution and access logs enabled

[GoGoris]

Using the Api Gateway logsubscription support with only execution logging enabled fails with the error "Unresolved resource dependencies [ApiGatewayLogGroup] in the Resources block of the template" because serverless creates this logGroup conditionally based on logs.restApi.accessLogging.

To reproduce add the following config in your serverless.yml:

 logs:
    restApi:
      executionLogging: true
      accessLogging: false

The reverse problem probably exists as well when accessLogging is enabled without executionLogging.