Remove pointer types where possible

[blkt]

Most of the types related to Trusty v2 API contain pointers since they're declared optional in openapi spec, but it is sometimes impossible to receive a null value.

We should reduce the number of pointers for values that have reasonable default values or can't really be null. Note that this requires checking openapi Spec accurately as well as consulting developers. Also, it might be reasonable to ask for a more detailed openapi spec.