Change addFieldValidationError to addValidationError

[timleslie]

This simplifies the API while making the implementation more consistent with the defined types. A future major release will remove the deprecated addFieldValidationError function.

[changeset-bot]

🦋 Changeset detected

Latest commit: 58f9378

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@keystone-next/fields	Patch
@keystone-next/keystone	Patch
@keystone-next/test-utils-legacy	Patch

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