Implement declarative defaults by using educe crate #249
Description
Current design of FleetAddonConfig CRD expects to default missing resource to a set of values, which should suffice for the initial usage of the provider. However these defaults are not always clear, and are more scattered across the code.
To address this issue, we can use https://crates.io/crates/educe, which will provide simplified alternative to a manual impl Default, in a way that makes it clear on a glance which values are set if the field is missing or defaulted.