Deduplicate and disambiguate containers by PartialEq

[clux]

a dumb attempt to fix #298 and #66

Encapsulates Output vector and forces all push calls to instead go through a public insert fn that checks for uniqueness and suffixes existing named structs that differ in other ways.

Equality is determined by an ad-hoc PartialEq on both Container and Vec. Have included the fields I think are important for equality. In particular, types, names, serde annots. Doc strings are ignored.

Note this changes tests to call a new, consuming .output() rather than .0 since the vector is now private.

[clux]

@sebhoss quick PoC that might help

[sebhoss]

This works almost perfectly - love it! See metio/kube-custom-resources-rs#441 for lots of stuff that now can be generated. There are only 2 remaining CRDs that do not work and they are kinda special:

1. ephemeralrunners.actions.github.com: Has a .spec.spec field (YAML) and therefore kopium generates two EphemeralRunnerSpec structs
2. nexususers.edp.epam.com: Has a .spec.status field (YAML) and therefore kopium generates two NexusUserStatus structs (or actually 1 enum for the field and 1 struct for the actual status resource)

I think both can be fixed if the new Output struct knows about the root kind and deduplicates against that, e.g., if it encounters <kind>Spec or <kind>Status as a potential new container to add, it knows that those already exist even though they are not part of its internal vector?