Rather than an "all or nothing" approach to defining a custom conversion
function (which seems destined to cause problems eventually), this is an
attempt to make it possible to call the auto-generated code and then "fix it
up".
Specifically, consider you have a fooBar struct. If you don't define a
conversion for FooBar, you will get a generated function like:
convert_v1_FooBar_To_api_FooBar()
Before this PR, if you define your own conversion function, you get no
generated function. After this PR you get:
autoconvert_v1_FooBar_To_api_FooBar()
...which you can call yourself in your custom function.
A lot of packages use StringSet, but they don't use anything else from
the util package. Moving StringSet into another package will shrink
their dependency trees significantly.
OpenShift uses multiple API packages (types are split) which
Kube will also eventually have as we introduce more plugins.
These changes make the generators able to handle importing different
API object packages into a single generator function.
