fix convert transforms toType field validation

[ravilr]

Description of your changes

• Updates Add support for convert transforms from JSON to object/array #4524

Updates the toType enum validation to include array instead of list. the docs PR crossplane/docs#541 already captures it as array.

On the xp master and v1.13.2-up.2 release currently, kubectl apply'ing a composition with transforms[].convert.toType set to array results in validation error:

the Composition "compose-v1alpha1.example.com" is invalid: 
* spec.resources[1].patches[3].transforms[0].convert.toType: Unsupported value: "array": supported values: "string", "int", "int64", "bool", "float64", "object", "list"

trying to apply with list also results in validation error:

The Composition "compose-v1alpha1.example.com" is invalid: 
* spec.resources[1].patches[3].transforms[0].convert.toType: Invalid value: "list": invalid type

With this change, a transforms[].convert.toType set to array, applies fine.

Fixes #

I have:

• Read and followed Crossplane's contribution process.
• Added or updated unit tests.
• Added or updated e2e tests, if necessary. (check with reviewers/maintainers if you're unsure whether E2E tests are necessary for the change).
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR, if necessary.
• Opened a PR updating the docs, if necessary.

[ravilr]

cc @phisco since you responded to this in the crossplane slack general channel. 🙏

[phisco]

Looking good, thanks @ravilr!