Require generated request body flags in airflowctl

[ibobgunardi]

Generated airflowctl commands expand request-body models into CLI flags, but required Pydantic fields were still optional to argparse. That let the command reach request-body validation before telling the user what was missing.

This passes field_info.is_required() through when building those flags, so commands like connections create report missing required fields as normal CLI arguments.

closes: #57721

Tests:

• .venv\Scripts\python.exe -m pytest airflow-ctl\tests\airflow_ctl\ctl\test_cli_config.py -q --confcutdir=airflow-ctl\tests\airflow_ctl\ctl
• .venv\Scripts\python.exe -m py_compile airflow-ctl\src\airflowctl\ctl\cli_config.py airflow-ctl\tests\airflow_ctl\ctl\test_cli_config.py

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Was generative AI tooling used to co-author this PR?

• Yes (OpenAI Codex)

Generated-by: OpenAI Codex following the guidelines

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• Read the Pull Request Guidelines for more information. Note: commit author/co-author name and email in commits become permanently public when merged.
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• When adding dependency, check compliance with the ASF 3rd Party License Policy.
• For significant user-facing changes create newsfragment: {pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.