feat: support field-level resolvers in the model

[fossamagna]

Problem

Issue number, if available:

aws-amplify/amplify-category-api#3306

Changes

This pull request introduces support for field-level resolvers (handlers) in the @aws-amplify/data-schema package, allowing developers to attach custom logic directly to individual fields in their models. The implementation includes updates to the schema builder API, schema processing logic, and related tests and documentation.

Field-level handler support:

• Added a new .handler() method to the ModelField builder, enabling the attachment of field-level resolvers (handlers) to fields. This is reflected in both the type definitions and the runtime implementation (ModelField.ts).

Corresponding docs PR, if applicable:

Validation

• Unit Tests (Added new tests and snapshots to verify that field-level handlers can be attached and are correctly represented in the generated schema.)

Checklist

• If this PR includes a functional change to the runtime or type-level behavior of the code, I have added or updated automated test coverage for this change. (see Testing Strategy README)
• If this PR requires a docs update, I have linked to that docs PR above.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[changeset-bot]

🦋 Changeset detected

Latest commit: 975f3fc

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

This PR includes changesets to release 1 package

Name	Type
@aws-amplify/data-schema	Minor

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