Move user-facing utilities from airflow.utils.* to Task SDK definitions

### Description

Move user-facing utilities from airflow.utils.* directly into Task SDK definition modules where they logically belong, creating deprecation shims for backward compatibility.

Files to move:
- airflow.utils.state → airflow.sdk.definitions.state
- airflow.utils.trigger_rule → airflow.sdk.definitions.trigger_rule
- airflow.utils.weight_rule → airflow.sdk.definitions.weight_rule
- airflow.utils.types → airflow.sdk.definitions.types
- airflow.utils.operator_resources → airflow.sdk.definitions.resources
- airflow.utils.task_group → merge into airflow.sdk.definitions.taskgroup
- airflow.utils.context → merge into airflow.sdk.definitions.context
- airflow.utils.decorators → merge into airflow.sdk.definitions.decorators
- airflow.utils.module_loading → airflow.sdk.definitions._internal.module_loading
- airflow.utils.helpers → airflow.sdk.definitions._internal.templating

### Use case/motivation

_No response_

### Related issues

https://github.com/apache/airflow/issues/51671

### Are you willing to submit a PR?

- [x] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start by comparing the listed airflow.utils modules with their airflow.sdk.definitions targets, including the taskgroup, context, decorators, _internal.module_loading, and _internal.templating modules. Read related issue #51671 before planning the migration. Done means the utilities are in the specified SDK locations and the old paths retain backward-compatible deprecation shims.

Written by the indexing model from the issue text.