crd-from-oas: union discriminator values derived from variant names produce awkward identifiers (e.g. oIDC)

[tao12345666333]

Problem Statement

The crd-from-oas generator derives CRD union discriminator values (the type enum) from Go variant type names: extractVariantNames strips common prefixes/suffixes, then a lower-first camelCase conversion produces the final value. For OIDCIdentityProviderConfig this yields oIDC — an awkward, error-prone, user-facing value in the PortalIdentityProviderRequest CRD (spec.config.type: oIDC, also the JSON field name oIDC).

The upstream OpenAPI spec already defines a clean enum for this purpose (IdentityProviderType: oidc / saml), but the generator does not use it for the discriminator.

Proposed Solution

Candidate approaches (not mutually exclusive):

1. Use the spec's own type enum values as union discriminator values when available.
2. Add a per-union discriminator/variant-name override in crd-from-oas/config.yaml.
3. Improve initialism handling in the lower-first camelCase conversion (lowercase the whole leading initialism run: OIDC → oidc).

Note: oIDC has shipped in v2.3.0 (and exists on release/2.2.x), so changing the enum value is a CRD breaking change. Any fix likely needs to wait for a CRD version bump (e.g. v1alpha1 → v1alpha2) or a major release window.

Additional Information

• Derivation chain: extractVariantNames / uniqueUnionDiscriminatorValues in crd-from-oas/pkg/generator/generator.go (~L3945) → lower-first camelCase (jsonName).
• Impact scan: oIDC is currently the only awkward discriminator value across all generated API types (portalSAML, tls_server, etc. are all fine).
• Surfaced during review of feat: generate GetForUID for Konnect PortalIdentityProviderRequest #3956.

Acceptance Criteria

• Documentation is updated with this new feature / enhancement (no user-facing docs change expected; the CRD schema itself is the documentation)
• Tests are added for this feature / enhancement
• Helm chart is updated to work with this feature / enhancement (no chart changes needed)
• As a user, I can use clean, idiomatic discriminator values (e.g. oidc / saml) in PortalIdentityProviderRequest manifests

[tao12345666333]

The content mentioned in this issue does not affect functionality; it is a user experience issue.