Add a brute force option to re-use identical structs

[clux]

Currently, it's impossible for kopium to detect similar structs re-used at different hierarchies because the schemas all have to be inlined and we cannot use $ref in schemas. kubernetes/kubernetes#62872

Suggestion

We should try to brute-force compare all structs (field names + types) to all previously seen structs in the analyzer to deduplicate so that we don't generate 3 different structs for things such as livenessProbe, resources, MatchLabels (under different names).

We already have the skeletons of such code, but it only checks for a few known ones like Condition here and it's enabled toggled under a flag (default enabled) --no-condition.

If we pass existing state into the extractor functions (such as extract_container) we can then inspect current state before adding duplicates (ensuring we only take the first instance of a struct) via something like is_duplicate_struct. It would also avoid having an awkward O(n^2) algorithm at the end.

My thinking is that it might not be a particularly heavy operation on (at most) a few hundred kB of schema data.

Limitations

This would not solve the problem where we are generating a type for something know; e.g. something like Condition might be deduplicated with this algorithm alone, but it would not point to the correct upstream type in e.g. k8s-openapi without futher logic.

This is probably fine however; it allows overrides to be done more easily (change / elide one struct rather than find and replace multiple), and it's a good stepping stone towards identifying them with upstream variants (such as is done for Condition).

More Context

• improvement(dev-ex): compatible/identical types should be aliased and reused where possible gateway-api-rs#38
• Using component refs to types in generated schema kube#1667

[shaneutt]

+1, this would be very helpful for kube-rs/gateway-api-rs#38